fix(@angular-devkit/architect): properly subscribe to error handlers

If an error is reported but ANY subscription have an undefined error handler, RxJS
reports the error to the "host platform" (it setTimeout(() => throw error)). Since
we properly handle errors in some places, but should ignore them in others (e.g.
we handle errors on the outboundBus, so the output subscription should ignore it),
we still need to subscribe to error, just ignore it.

Author: hansl

packages/angular_devkit/architect/src/schedule-by-name.ts

@@ -6,8 +6,8 @@
  * found in the LICENSE file at https://angular.io/license
  */
 import { experimental, json, logging } from '@angular-devkit/core';
-import { Subscription } from 'rxjs';
-import { first, ignoreElements, map, shareReplay } from 'rxjs/operators';
+import { EMPTY, Subscription } from 'rxjs';
+import { catchError, first, ignoreElements, map, share, shareReplay, tap } from 'rxjs/operators';
 import {
   BuilderInfo,
   BuilderInput,
@@ -60,46 +60,55 @@ export async function scheduleByName(
       if (event.kind === experimental.jobs.JobOutboundMessageKind.Start) {
         job.input.next(message);
       }
-    });
+    }, () => {});
   } else {
     job.input.next(message);
   }
 
   const logChannelSub = job.getChannel<logging.LogEntry>('log').subscribe(entry => {
     logger.next(entry);
-  });
+  }, () => {});
 
-  const s = job.outboundBus.subscribe(
-    undefined,
-    undefined,
-    () => {
+  const s = job.outboundBus.subscribe({
+    error() {},
+    complete() {
       s.unsubscribe();
       logChannelSub.unsubscribe();
       if (stateSubscription) {
         stateSubscription.unsubscribe();
       }
     },
-  );
+  });
   const output = job.output.pipe(
     map(output => ({
       ...output,
       ...options.target ? { target: options.target } : 0,
       info,
     } as BuilderOutput)),
+    shareReplay(),
   );
 
+  // Start the builder.
+  output.pipe(first()).subscribe({
+    error() {},
+  });
+
   return {
     id,
     info,
-    result: output.pipe(first()).toPromise(),
+    // This is a getter so that it always returns the next output, and not the same one.
+    get result() { return output.pipe(first()).toPromise(); },
     output,
     progress: job.getChannel<BuilderProgressReport>('progress', progressSchema).pipe(
       shareReplay(1),
     ),
     stop() {
       job.stop();
 
-      return output.pipe(ignoreElements()).toPromise();
+      return job.outboundBus.pipe(
+        ignoreElements(),
+        catchError(() => EMPTY),
+      ).toPromise();
     },
   };
 }