diff --git a/common/legacy_value.cc b/common/legacy_value.cc
index 5c81fdacb..7fbf16732 100644
--- a/common/legacy_value.cc
+++ b/common/legacy_value.cc
@@ -700,7 +700,8 @@ absl::Status LegacyMapValue::Get(
     case ValueKind::kString:
       break;
     default:
-      return InvalidMapKeyTypeError(key.kind());
+      *result = ErrorValue(InvalidMapKeyTypeError(key.kind()));
+      return absl::OkStatus();
   }
   CEL_ASSIGN_OR_RETURN(auto cel_key, LegacyValue(arena, key));
   auto cel_value = impl_->Get(arena, cel_key);
@@ -732,7 +733,7 @@ absl::StatusOr<bool> LegacyMapValue::Find(
     case ValueKind::kString:
       break;
     default:
-      return InvalidMapKeyTypeError(key.kind());
+      *result = ErrorValue(InvalidMapKeyTypeError(key.kind()));
   }
   CEL_ASSIGN_OR_RETURN(auto cel_key, LegacyValue(arena, key));
   auto cel_value = impl_->Get(arena, cel_key);
@@ -764,11 +765,17 @@ absl::Status LegacyMapValue::Has(
     case ValueKind::kString:
       break;
     default:
-      return InvalidMapKeyTypeError(key.kind());
+      *result = ErrorValue(InvalidMapKeyTypeError(key.kind()));
+      return absl::OkStatus();
   }
   CEL_ASSIGN_OR_RETURN(auto cel_key, LegacyValue(arena, key));
-  CEL_ASSIGN_OR_RETURN(auto has, impl_->Has(cel_key));
-  *result = BoolValue{has};
+  absl::StatusOr<bool> has = impl_->Has(cel_key);
+  if (!has.ok()) {
+    *result = ErrorValue(std::move(has).status());
+    return absl::OkStatus();
+  }
+
+  *result = BoolValue(*has);
   return absl::OkStatus();
 }
 
diff --git a/common/values/custom_map_value.h b/common/values/custom_map_value.h
index 9e840e07f..ca6e1e025 100644
--- a/common/values/custom_map_value.h
+++ b/common/values/custom_map_value.h
@@ -225,7 +225,7 @@ class CustomMapValueInterface {
   // Returns the number of entries in this map.
   virtual size_t Size() const = 0;
 
-  // See the corresponding member function of `MapValueInterface` for
+  // See the corresponding member function of `MapValue` for
   // documentation.
   virtual absl::Status ListKeys(
       const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,
@@ -233,7 +233,7 @@ class CustomMapValueInterface {
       google::protobuf::Arena* absl_nonnull arena,
       ListValue* absl_nonnull result) const = 0;
 
-  // See the corresponding member function of `MapValueInterface` for
+  // See the corresponding member function of `MapValue` for
   // documentation.
   virtual absl::Status ForEach(
       ForEachCallback callback,
@@ -347,7 +347,7 @@ class CustomMapValue final
 
   size_t Size() const;
 
-  // See the corresponding member function of `MapValueInterface` for
+  // See the corresponding member function of `MapValue` for
   // documentation.
   absl::Status Get(const Value& key,
                    const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,
@@ -356,7 +356,7 @@ class CustomMapValue final
                    Value* absl_nonnull result) const;
   using MapValueMixin::Get;
 
-  // See the corresponding member function of `MapValueInterface` for
+  // See the corresponding member function of `MapValue` for
   // documentation.
   absl::StatusOr<bool> Find(
       const Value& key,
@@ -365,7 +365,7 @@ class CustomMapValue final
       google::protobuf::Arena* absl_nonnull arena, Value* absl_nonnull result) const;
   using MapValueMixin::Find;
 
-  // See the corresponding member function of `MapValueInterface` for
+  // See the corresponding member function of `MapValue` for
   // documentation.
   absl::Status Has(const Value& key,
                    const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,
@@ -374,7 +374,7 @@ class CustomMapValue final
                    Value* absl_nonnull result) const;
   using MapValueMixin::Has;
 
-  // See the corresponding member function of `MapValueInterface` for
+  // See the corresponding member function of `MapValue` for
   // documentation.
   absl::Status ListKeys(
       const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,
@@ -386,7 +386,7 @@ class CustomMapValue final
   // documentation.
   using ForEachCallback = typename CustomMapValueInterface::ForEachCallback;
 
-  // See the corresponding member function of `MapValueInterface` for
+  // See the corresponding member function of `MapValue` for
   // documentation.
   absl::Status ForEach(
       ForEachCallback callback,
@@ -394,7 +394,7 @@ class CustomMapValue final
       google::protobuf::MessageFactory* absl_nonnull message_factory,
       google::protobuf::Arena* absl_nonnull arena) const;
 
-  // See the corresponding member function of `MapValueInterface` for
+  // See the corresponding member function of `MapValue` for
   // documentation.
   absl::StatusOr<absl_nonnull ValueIteratorPtr> NewIterator() const;
 
diff --git a/common/values/legacy_map_value.h b/common/values/legacy_map_value.h
index 31865a873..c83b7fc2f 100644
--- a/common/values/legacy_map_value.h
+++ b/common/values/legacy_map_value.h
@@ -102,7 +102,7 @@ class LegacyMapValue final
 
   size_t Size() const;
 
-  // See the corresponding member function of `MapValueInterface` for
+  // See the corresponding member function of `MapValue` for
   // documentation.
   absl::Status Get(const Value& key,
                    const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,
@@ -111,7 +111,7 @@ class LegacyMapValue final
                    Value* absl_nonnull result) const;
   using MapValueMixin::Get;
 
-  // See the corresponding member function of `MapValueInterface` for
+  // See the corresponding member function of `MapValue` for
   // documentation.
   absl::StatusOr<bool> Find(
       const Value& key,
@@ -120,7 +120,7 @@ class LegacyMapValue final
       google::protobuf::Arena* absl_nonnull arena, Value* absl_nonnull result) const;
   using MapValueMixin::Find;
 
-  // See the corresponding member function of `MapValueInterface` for
+  // See the corresponding member function of `MapValue` for
   // documentation.
   absl::Status Has(const Value& key,
                    const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,
@@ -129,7 +129,7 @@ class LegacyMapValue final
                    Value* absl_nonnull result) const;
   using MapValueMixin::Has;
 
-  // See the corresponding member function of `MapValueInterface` for
+  // See the corresponding member function of `MapValue` for
   // documentation.
   absl::Status ListKeys(
       const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,
@@ -137,11 +137,11 @@ class LegacyMapValue final
       google::protobuf::Arena* absl_nonnull arena, ListValue* absl_nonnull result) const;
   using MapValueMixin::ListKeys;
 
-  // See the corresponding type declaration of `MapValueInterface` for
+  // See the corresponding type declaration of `MapValue` for
   // documentation.
   using ForEachCallback = typename CustomMapValueInterface::ForEachCallback;
 
-  // See the corresponding member function of `MapValueInterface` for
+  // See the corresponding member function of `MapValue` for
   // documentation.
   absl::Status ForEach(
       ForEachCallback callback,
diff --git a/common/values/map_value.h b/common/values/map_value.h
index ffbdea6c9..b6e69ea57 100644
--- a/common/values/map_value.h
+++ b/common/values/map_value.h
@@ -15,10 +15,16 @@
 // IWYU pragma: private, include "common/value.h"
 // IWYU pragma: friend "common/value.h"
 
-// `MapValue` represents values of the primitive `map` type. `MapValueView`
-// is a non-owning view of `MapValue`. `MapValueInterface` is the abstract
-// base class of implementations. `MapValue` and `MapValueView` act as smart
-// pointers to `MapValueInterface`.
+// `MapValue` represents values of the primitive `map` type. It provides a
+// unified interface for accessing map contents, regardless of the underlying
+// implementation (e.g., JSON, protobuf map field, or custom implementation).
+//
+// Public member functions:
+// - `IsEmpty()` / `Size()`: Query map size.
+// - `Get()` / `Find()` / `Has()`: Access entries by key.
+// - `ListKeys()` / `NewIterator()` / `ForEach()`: Iterate over entries.
+// - `ConvertToJson()` / `ConvertToJsonObject()`: JSON conversion.
+// - `IsCustom()` / `AsCustom()` / `GetCustom()`: Access custom implementation.
 
 #ifndef THIRD_PARTY_CEL_CPP_COMMON_VALUES_MAP_VALUE_H_
 #define THIRD_PARTY_CEL_CPP_COMMON_VALUES_MAP_VALUE_H_
@@ -54,7 +60,6 @@
 
 namespace cel {
 
-class MapValueInterface;
 class MapValue;
 class Value;
 
@@ -119,8 +124,13 @@ class MapValue final : private common_internal::MapValueMixin<MapValue> {
 
   absl::StatusOr<size_t> Size() const;
 
-  // See the corresponding member function of `MapValueInterface` for
-  // documentation.
+  // `Get` sets the value `result` to (via `result`) the value associated with
+  // `key`. If `key` is not found, `no such key` is set to `result`. If an error
+  // occurs (e.g., invalid key type), an `no such key` is returned.
+  //
+  // A non-ok status may be returned if an unexpected error is encountered or to
+  // propagate an error from a custom implementation, in which case `result` is
+  // unspecified.
   absl::Status Get(const Value& key,
                    const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,
                    google::protobuf::MessageFactory* absl_nonnull message_factory,
@@ -128,8 +138,13 @@ class MapValue final : private common_internal::MapValueMixin<MapValue> {
                    Value* absl_nonnull result) const;
   using MapValueMixin::Get;
 
-  // See the corresponding member function of `MapValueInterface` for
-  // documentation.
+  // `Find` returns `true` if `key` is found in the map, and stores the
+  // associated value in `result`. If `key` is not found, `false` is returned
+  // and `result` is unchanged.
+  //
+  // A non-ok status may be returned if an unexpected error is encountered or to
+  // propagate an error from a custom implementation, in which case `result` is
+  // unspecified.
   absl::StatusOr<bool> Find(
       const Value& key,
       const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,
@@ -137,8 +152,13 @@ class MapValue final : private common_internal::MapValueMixin<MapValue> {
       google::protobuf::Arena* absl_nonnull arena, Value* absl_nonnull result) const;
   using MapValueMixin::Find;
 
-  // See the corresponding member function of `MapValueInterface` for
-  // documentation.
+  // `Has` returns `true` if `key` is found in the map, and stores the BoolValue
+  // result in `result`. In case of an error, the result is set to an
+  // ErrorValue.
+  //
+  // A non-ok status may be returned if an unexpected error is encountered or to
+  // propagate an error from a custom implementation, in which case `result` is
+  // unspecified.
   absl::Status Has(const Value& key,
                    const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,
                    google::protobuf::MessageFactory* absl_nonnull message_factory,
@@ -146,28 +166,25 @@ class MapValue final : private common_internal::MapValueMixin<MapValue> {
                    Value* absl_nonnull result) const;
   using MapValueMixin::Has;
 
-  // See the corresponding member function of `MapValueInterface` for
-  // documentation.
+  // `ListKeys` returns a `ListValue` containing all keys in the map.
   absl::Status ListKeys(
       const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,
       google::protobuf::MessageFactory* absl_nonnull message_factory,
       google::protobuf::Arena* absl_nonnull arena, ListValue* absl_nonnull result) const;
   using MapValueMixin::ListKeys;
 
-  // See the corresponding type declaration of `MapValueInterface` for
-  // documentation.
+  // `ForEachCallback` is the callback type for `ForEach`.
   using ForEachCallback = typename CustomMapValueInterface::ForEachCallback;
 
-  // See the corresponding member function of `MapValueInterface` for
-  // documentation.
+  // `ForEach` calls `callback` for each entry in the map. Iteration continues
+  // until all entries are visited or `callback` returns an error or `false`.
   absl::Status ForEach(
       ForEachCallback callback,
       const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,
       google::protobuf::MessageFactory* absl_nonnull message_factory,
       google::protobuf::Arena* absl_nonnull arena) const;
 
-  // See the corresponding member function of `MapValueInterface` for
-  // documentation.
+  // `NewIterator` returns a new iterator for the map.
   absl::StatusOr<absl_nonnull ValueIteratorPtr> NewIterator() const;
 
   // Returns `true` if this value is an instance of a custom map value.
diff --git a/common/values/null_value.h b/common/values/null_value.h
index 53c3161a1..d4d05dba3 100644
--- a/common/values/null_value.h
+++ b/common/values/null_value.h
@@ -37,8 +37,7 @@ namespace cel {
 class Value;
 class NullValue;
 
-// `NullValue` represents values of the primitive `duration` type.
-
+// `NullValue` represents the CEL `null` value.
 class NullValue final : private common_internal::ValueMixin<NullValue> {
  public:
   static constexpr ValueKind kKind = ValueKind::kNull;
diff --git a/common/values/parsed_json_map_value.h b/common/values/parsed_json_map_value.h
index b20fe032b..ba8d3490d 100644
--- a/common/values/parsed_json_map_value.h
+++ b/common/values/parsed_json_map_value.h
@@ -132,7 +132,7 @@ class ParsedJsonMapValue final
 
   size_t Size() const;
 
-  // See the corresponding member function of `MapValueInterface` for
+  // See the corresponding member function of `MapValue` for
   // documentation.
   absl::Status Get(const Value& key,
                    const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,
@@ -141,7 +141,7 @@ class ParsedJsonMapValue final
                    Value* absl_nonnull result) const;
   using MapValueMixin::Get;
 
-  // See the corresponding member function of `MapValueInterface` for
+  // See the corresponding member function of `MapValue` for
   // documentation.
   absl::StatusOr<bool> Find(
       const Value& key,
@@ -150,7 +150,7 @@ class ParsedJsonMapValue final
       google::protobuf::Arena* absl_nonnull arena, Value* absl_nonnull result) const;
   using MapValueMixin::Find;
 
-  // See the corresponding member function of `MapValueInterface` for
+  // See the corresponding member function of `MapValue` for
   // documentation.
   absl::Status Has(const Value& key,
                    const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,
@@ -159,7 +159,7 @@ class ParsedJsonMapValue final
                    Value* absl_nonnull result) const;
   using MapValueMixin::Has;
 
-  // See the corresponding member function of `MapValueInterface` for
+  // See the corresponding member function of `MapValue` for
   // documentation.
   absl::Status ListKeys(
       const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,
@@ -167,11 +167,11 @@ class ParsedJsonMapValue final
       google::protobuf::Arena* absl_nonnull arena, ListValue* absl_nonnull result) const;
   using MapValueMixin::ListKeys;
 
-  // See the corresponding type declaration of `MapValueInterface` for
+  // See the corresponding type declaration of `MapValue` for
   // documentation.
   using ForEachCallback = typename CustomMapValueInterface::ForEachCallback;
 
-  // See the corresponding member function of `MapValueInterface` for
+  // See the corresponding member function of `MapValue` for
   // documentation.
   absl::Status ForEach(
       ForEachCallback callback,
diff --git a/common/values/parsed_map_field_value.h b/common/values/parsed_map_field_value.h
index 3478f75bc..21d686bfd 100644
--- a/common/values/parsed_map_field_value.h
+++ b/common/values/parsed_map_field_value.h
@@ -117,7 +117,7 @@ class ParsedMapFieldValue final
 
   size_t Size() const;
 
-  // See the corresponding member function of `MapValueInterface` for
+  // See the corresponding member function of `MapValue` for
   // documentation.
   absl::Status Get(const Value& key,
                    const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,
@@ -126,7 +126,7 @@ class ParsedMapFieldValue final
                    Value* absl_nonnull result) const;
   using MapValueMixin::Get;
 
-  // See the corresponding member function of `MapValueInterface` for
+  // See the corresponding member function of `MapValue` for
   // documentation.
   absl::StatusOr<bool> Find(
       const Value& key,
@@ -135,7 +135,7 @@ class ParsedMapFieldValue final
       google::protobuf::Arena* absl_nonnull arena, Value* absl_nonnull result) const;
   using MapValueMixin::Find;
 
-  // See the corresponding member function of `MapValueInterface` for
+  // See the corresponding member function of `MapValue` for
   // documentation.
   absl::Status Has(const Value& key,
                    const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,
@@ -144,7 +144,7 @@ class ParsedMapFieldValue final
                    Value* absl_nonnull result) const;
   using MapValueMixin::Has;
 
-  // See the corresponding member function of `MapValueInterface` for
+  // See the corresponding member function of `MapValue` for
   // documentation.
   absl::Status ListKeys(
       const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,
@@ -152,11 +152,11 @@ class ParsedMapFieldValue final
       google::protobuf::Arena* absl_nonnull arena, ListValue* absl_nonnull result) const;
   using MapValueMixin::ListKeys;
 
-  // See the corresponding type declaration of `MapValueInterface` for
+  // See the corresponding type declaration of `MapValue` for
   // documentation.
   using ForEachCallback = typename CustomMapValueInterface::ForEachCallback;
 
-  // See the corresponding member function of `MapValueInterface` for
+  // See the corresponding member function of `MapValue` for
   // documentation.
   absl::Status ForEach(
       ForEachCallback callback,
diff --git a/common/values/values.h b/common/values/values.h
index c9703dcbb..aaa6f8659 100644
--- a/common/values/values.h
+++ b/common/values/values.h
@@ -48,7 +48,6 @@ namespace cel {
 
 class ValueInterface;
 class ListValueInterface;
-class MapValueInterface;
 class StructValueInterface;
 
 class Value;
diff --git a/eval/eval/equality_steps.cc b/eval/eval/equality_steps.cc
index e134069d5..d720302e4 100644
--- a/eval/eval/equality_steps.cc
+++ b/eval/eval/equality_steps.cc
@@ -132,15 +132,11 @@ class IterativeEqualityStep : public ExpressionStepBase {
 absl::StatusOr<Value> EvaluateInMap(ExecutionFrameBase& frame,
                                     const Value& item,
                                     const MapValue& container) {
-  absl::StatusOr<Value> result = {BoolValue(false)};
   switch (item.kind()) {
     case ValueKind::kBool:
     case ValueKind::kString:
     case ValueKind::kInt:
     case ValueKind::kUint:
-      result = container.Has(item, frame.descriptor_pool(),
-                             frame.message_factory(), frame.arena());
-      break;
     case ValueKind::kDouble:
       break;
     default:
@@ -148,9 +144,12 @@ absl::StatusOr<Value> EvaluateInMap(ExecutionFrameBase& frame,
           cel::runtime_internal::CreateNoMatchingOverloadError(
               cel::builtin::kIn));
   }
+  Value result;
+  CEL_RETURN_IF_ERROR(container.Has(item, frame.descriptor_pool(),
+                                    frame.message_factory(), frame.arena(),
+                                    &result));
 
-  if (result.ok() && result.value().IsBool() &&
-      result.value().GetBool().NativeValue()) {
+  if (result.IsTrue()) {
     return result;
   }
 
@@ -159,10 +158,10 @@ absl::StatusOr<Value> EvaluateInMap(ExecutionFrameBase& frame,
                         ? Number::FromDouble(item.GetDouble().NativeValue())
                         : Number::FromUint64(item.GetUint().NativeValue());
     if (number.LosslessConvertibleToInt()) {
-      result = container.Has(IntValue(number.AsInt()), frame.descriptor_pool(),
-                             frame.message_factory(), frame.arena());
-      if (result.ok() && result.value().IsBool() &&
-          result.value().GetBool().NativeValue()) {
+      CEL_RETURN_IF_ERROR(
+          container.Has(IntValue(number.AsInt()), frame.descriptor_pool(),
+                        frame.message_factory(), frame.arena(), &result));
+      if (result.IsTrue()) {
         return result;
       }
     }
@@ -173,21 +172,16 @@ absl::StatusOr<Value> EvaluateInMap(ExecutionFrameBase& frame,
                         ? Number::FromDouble(item.GetDouble().NativeValue())
                         : Number::FromInt64(item.GetInt().NativeValue());
     if (number.LosslessConvertibleToUint()) {
-      result =
+      CEL_RETURN_IF_ERROR(
           container.Has(UintValue(number.AsUint()), frame.descriptor_pool(),
-                        frame.message_factory(), frame.arena());
-      if (result.ok() && result.value().IsBool() &&
-          result.value().GetBool().NativeValue()) {
+                        frame.message_factory(), frame.arena(), &result));
+      if (result.IsTrue()) {
         return result;
       }
     }
   }
 
-  if (!result.ok()) {
-    return BoolValue(false);
-  }
-
-  return result;
+  return BoolValue(false);
 }
 
 absl::StatusOr<Value> EvaluateIn(ExecutionFrameBase& frame, const Value& item,
diff --git a/eval/public/builtin_func_test.cc b/eval/public/builtin_func_test.cc
index 037fa8345..b73a2dc55 100644
--- a/eval/public/builtin_func_test.cc
+++ b/eval/public/builtin_func_test.cc
@@ -1632,7 +1632,8 @@ TEST_F(BuiltinsTest, TestMapInError) {
     CelValue result_value;
     ASSERT_NO_FATAL_FAILURE(PerformRun(
         builtin::kIn, {}, {key, CelValue::CreateMap(&cel_map)}, &result_value));
-    EXPECT_TRUE(result_value.IsBool());
+    ASSERT_TRUE(result_value.IsBool())
+        << key.DebugString() << " : " << result_value.DebugString();
     EXPECT_FALSE(result_value.BoolOrDie());
   }
 
diff --git a/eval/public/cel_type_registry.h b/eval/public/cel_type_registry.h
index 0c01eb8e9..3fb80bcea 100644
--- a/eval/public/cel_type_registry.h
+++ b/eval/public/cel_type_registry.h
@@ -28,7 +28,6 @@
 #include "base/type_provider.h"
 #include "eval/public/structs/legacy_type_adapter.h"
 #include "eval/public/structs/legacy_type_provider.h"
-#include "eval/public/structs/protobuf_descriptor_type_provider.h"
 #include "runtime/type_registry.h"
 #include "google/protobuf/descriptor.h"
 #include "google/protobuf/message.h"
@@ -139,11 +138,6 @@ class CelTypeRegistry {
  private:
   // Internal modern registry.
   cel::TypeRegistry modern_type_registry_;
-
-  // TODO(uncreated-issue/44): This is needed to inspect the registered legacy type
-  // providers for client tests. This can be removed when they are migrated to
-  // use the modern APIs.
-  std::shared_ptr<const ProtobufDescriptorProvider> legacy_type_provider_;
 };
 
 }  // namespace google::api::expr::runtime
diff --git a/eval/public/structs/field_access_impl.cc b/eval/public/structs/field_access_impl.cc
index 3b3cb9847..2bd9fff9d 100644
--- a/eval/public/structs/field_access_impl.cc
+++ b/eval/public/structs/field_access_impl.cc
@@ -139,8 +139,7 @@ class FieldAccessor {
           case FieldDescriptor::TYPE_BYTES:
             return CelValue::CreateBytesView(value);
           default:
-            return absl::Status(absl::StatusCode::kInvalidArgument,
-                                "Error handling C++ string conversion");
+            break;
         }
         break;
       }
@@ -153,8 +152,7 @@ class FieldAccessor {
         return CelValue::CreateInt64(enum_value);
       }
       default:
-        return absl::Status(absl::StatusCode::kInvalidArgument,
-                            "Unhandled C++ type conversion");
+        break;
     }
     return absl::Status(absl::StatusCode::kInvalidArgument,
                         "Unhandled C++ type conversion");
diff --git a/eval/public/structs/proto_message_type_adapter_test.cc b/eval/public/structs/proto_message_type_adapter_test.cc
index 088d20d48..32608bc3f 100644
--- a/eval/public/structs/proto_message_type_adapter_test.cc
+++ b/eval/public/structs/proto_message_type_adapter_test.cc
@@ -69,8 +69,8 @@ class ProtoMessageTypeAccessorTest : public testing::TestWithParam<bool> {
     bool use_generic_instance = GetParam();
     if (use_generic_instance) {
       // implementation detail: in general, type info implementations may
-      // return a different accessor object based on the messsage instance, but
-      // this implemenation returns the same one no matter the message.
+      // return a different accessor object based on the message instance, but
+      // this implementation returns the same one no matter the message.
       return *GetGenericProtoTypeInfoInstance().GetAccessApis(dummy_);
 
     } else {
diff --git a/runtime/standard/container_membership_functions.cc b/runtime/standard/container_membership_functions.cc
index 9f5ca3755..cc0638429 100644
--- a/runtime/standard/container_membership_functions.cc
+++ b/runtime/standard/container_membership_functions.cc
@@ -174,15 +174,16 @@ absl::Status RegisterMapMembershipFunctions(FunctionRegistry& registry,
           const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,
           google::protobuf::MessageFactory* absl_nonnull message_factory,
           google::protobuf::Arena* absl_nonnull arena) -> absl::StatusOr<Value> {
-    auto result =
-        map_value.Has(BoolValue(key), descriptor_pool, message_factory, arena);
-    if (result.ok()) {
-      return std::move(*result);
+    Value has;
+    CEL_RETURN_IF_ERROR(map_value.Has(BoolValue(key), descriptor_pool,
+                                      message_factory, arena, &has));
+    if (has.IsTrue()) {
+      return has;
     }
     if (enable_heterogeneous_equality) {
       return BoolValue(false);
     }
-    return ErrorValue(result.status());
+    return has;
   };
 
   auto intKeyInSet =
@@ -191,27 +192,26 @@ absl::Status RegisterMapMembershipFunctions(FunctionRegistry& registry,
           const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,
           google::protobuf::MessageFactory* absl_nonnull message_factory,
           google::protobuf::Arena* absl_nonnull arena) -> absl::StatusOr<Value> {
-    auto result =
-        map_value.Has(IntValue(key), descriptor_pool, message_factory, arena);
+    Value result;
+    CEL_RETURN_IF_ERROR(map_value.Has(IntValue(key), descriptor_pool,
+                                      message_factory, arena, &result));
     if (enable_heterogeneous_equality) {
-      if (result.ok() && result->IsTrue()) {
-        return std::move(*result);
+      if (result.IsTrue()) {
+        return result;
       }
       Number number = Number::FromInt64(key);
       if (number.LosslessConvertibleToUint()) {
-        const auto& result =
-            map_value.Has(UintValue(number.AsUint()), descriptor_pool,
-                          message_factory, arena);
-        if (result.ok() && result->IsTrue()) {
-          return std::move(*result);
+        Value result_alt;
+        CEL_RETURN_IF_ERROR(map_value.Has(UintValue(number.AsUint()),
+                                          descriptor_pool, message_factory,
+                                          arena, &result_alt));
+        if (result_alt.IsTrue()) {
+          return result_alt;
         }
       }
       return BoolValue(false);
     }
-    if (!result.ok()) {
-      return ErrorValue(result.status());
-    }
-    return std::move(*result);
+    return result;
   };
 
   auto stringKeyInSet =
@@ -220,14 +220,16 @@ absl::Status RegisterMapMembershipFunctions(FunctionRegistry& registry,
           const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,
           google::protobuf::MessageFactory* absl_nonnull message_factory,
           google::protobuf::Arena* absl_nonnull arena) -> absl::StatusOr<Value> {
-    auto result = map_value.Has(key, descriptor_pool, message_factory, arena);
-    if (result.ok()) {
-      return std::move(*result);
+    Value result;
+    CEL_RETURN_IF_ERROR(
+        map_value.Has(key, descriptor_pool, message_factory, arena, &result));
+    if (result.IsBool()) {
+      return result;
     }
     if (enable_heterogeneous_equality) {
       return BoolValue(false);
     }
-    return ErrorValue(result.status());
+    return result;
   };
 
   auto uintKeyInSet =
@@ -236,26 +238,26 @@ absl::Status RegisterMapMembershipFunctions(FunctionRegistry& registry,
           const google::protobuf::DescriptorPool* absl_nonnull descriptor_pool,
           google::protobuf::MessageFactory* absl_nonnull message_factory,
           google::protobuf::Arena* absl_nonnull arena) -> absl::StatusOr<Value> {
-    const auto& result =
-        map_value.Has(UintValue(key), descriptor_pool, message_factory, arena);
+    Value has;
+    CEL_RETURN_IF_ERROR(map_value.Has(UintValue(key), descriptor_pool,
+                                      message_factory, arena, &has));
     if (enable_heterogeneous_equality) {
-      if (result.ok() && result->IsTrue()) {
-        return std::move(*result);
+      if (has.IsTrue()) {
+        return has;
       }
+      Value has_alt;
       Number number = Number::FromUint64(key);
       if (number.LosslessConvertibleToInt()) {
-        const auto& result = map_value.Has(
-            IntValue(number.AsInt()), descriptor_pool, message_factory, arena);
-        if (result.ok() && result->IsTrue()) {
-          return std::move(*result);
+        CEL_RETURN_IF_ERROR(map_value.Has(IntValue(number.AsInt()),
+                                          descriptor_pool, message_factory,
+                                          arena, &has_alt));
+        if (has.IsTrue()) {
+          return has;
         }
       }
       return BoolValue(false);
     }
-    if (!result.ok()) {
-      return ErrorValue(result.status());
-    }
-    return std::move(*result);
+    return has;
   };
 
   auto doubleKeyInSet =
@@ -265,17 +267,21 @@ absl::Status RegisterMapMembershipFunctions(FunctionRegistry& registry,
          google::protobuf::Arena* absl_nonnull arena) -> absl::StatusOr<Value> {
     Number number = Number::FromDouble(key);
     if (number.LosslessConvertibleToInt()) {
-      const auto& result = map_value.Has(
-          IntValue(number.AsInt()), descriptor_pool, message_factory, arena);
-      if (result.ok() && result->IsTrue()) {
-        return std::move(*result);
+      Value has;
+      CEL_RETURN_IF_ERROR(map_value.Has(IntValue(number.AsInt()),
+                                        descriptor_pool, message_factory, arena,
+                                        &has));
+      if (has.IsTrue()) {
+        return has;
       }
     }
     if (number.LosslessConvertibleToUint()) {
-      const auto& result = map_value.Has(
-          UintValue(number.AsUint()), descriptor_pool, message_factory, arena);
-      if (result.ok() && result->IsTrue()) {
-        return std::move(*result);
+      Value has;
+      CEL_RETURN_IF_ERROR(map_value.Has(UintValue(number.AsUint()),
+                                        descriptor_pool, message_factory, arena,
+                                        &has));
+      if (has.IsTrue()) {
+        return has;
       }
     }
     return BoolValue(false);