fix(@angular/build): safeguard Karma builder stream controller against closed state

When running Karma tests or when stream consumers (such as Architect test harness `executeOnce`) cancel the builder output stream early, both `ProgressNotifierReporter.onRunComplete` and `karma.Server` exit callbacks can attempt to enqueue results or close the `ReadableStreamController`.

Under WHATWG Streams specification rules, calling `.enqueue()` or `.close()` on a controller whose `desiredSize` is `null` (closed or cancelled) throws `TypeError [ERR_INVALID_STATE]: Invalid state: Controller is already closed`.

This change checks `controller.desiredSize !== null` and wraps enqueue/close calls in a try-catch block to gracefully handle closed controllers.

Author: clydin

packages/angular/build/src/builders/karma/application_builder.ts

@@ -85,8 +85,14 @@ export function execute(
 
       // Close the stream once the Karma server returns.
       karmaServer = new karma.Server(karmaConfig as Config, (exitCode) => {
-        controller.enqueue({ success: exitCode === 0 });
-        controller.close();
+        if (controller.desiredSize !== null) {
+          try {
+            controller.enqueue({ success: exitCode === 0 });
+            controller.close();
+          } catch {
+            // Stream controller may already be closed or cancelled
+          }
+        }
       });
 
       await karmaServer.start();

packages/angular/build/src/builders/karma/progress-reporter.ts

@@ -81,10 +81,12 @@ export function injectKarmaReporter(
     }
 
     onRunComplete = function (_browsers: unknown, results: RunCompleteInfo): void {
-      if (results.exitCode === 0) {
-        controller.enqueue({ success: true });
-      } else {
-        controller.enqueue({ success: false });
+      if (controller.desiredSize !== null) {
+        try {
+          controller.enqueue({ success: results.exitCode === 0 });
+        } catch {
+          // Stream controller may already be closed or cancelled
+        }
       }
     };
   }