BridgeJS: Skip type handle registration for unlinked modules

`js test` generates the glue from every test target's skeletons, but the
SwiftBuild build system links one binary per test target, so the eager
registration hit a missing export.

Author: kateinoigakukun

Plugins/BridgeJS/Sources/BridgeJSLink/BridgeJSLink.swift

@@ -351,7 +351,11 @@ public struct BridgeJSLink {
             for skeleton in skeletons {
                 guard skeleton.typeRegistrationEntries != nil else { continue }
                 let name = ABINameGenerator.typeRegistrationFunctionName(moduleName: skeleton.moduleName)
-                declarations.append("    \(JSGlueVariableScope.reservedInstance).exports[\"\(name)\"]();")
+                // The glue may describe more modules than the instance links in: `js test`
+                // generates it from every test target's skeletons, while the SwiftBuild
+                // build system produces one binary per test target. A module that isn't
+                // linked in can't have its types used either, so skip its registration.
+                declarations.append("    \(JSGlueVariableScope.reservedInstance).exports[\"\(name)\"]?.();")
             }
             declarations.append("}")
             declarations.append(contentsOf: GenericJSCodegen.runtimeHelperDeclarations())

Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/GenericImports.js

@@ -52,7 +52,7 @@ export async function createInstantiator(options, swift) {
         }
         __bjs_typeHandlesRegistered = true;
         instance.exports["bjs_core_register_type_handles"]();
-        instance.exports["bjs_TestModule_register_type_handles"]();
+        instance.exports["bjs_TestModule_register_type_handles"]?.();
     }
     function __bjs_codecForTypeId(typeId) {
         __bjs_registerTypeHandles();