fix(ngcc): provide a unique exit code for timeouts (#36838)

When ngcc fails due to a timeout waiting for another process
to complete, it was not failing with a unique exit code, so that it
was not possible to know if the process can be restarted; compared to
ngcc failing for some more fatal reason.

Now if ngcc exits because of a timeout, the exit code will be 177.

PR Close #36838

packages/compiler-cli/ngcc/main-ngcc.ts

@@ -24,7 +24,7 @@ if (require.main === module) {
       process.exitCode = 0;
     } catch (e) {
       console.error(e.stack || e.message);
-      process.exit(1);
+      process.exit(typeof e.code === 'number' ? e.code : 1);
     }
   })();
 }

packages/compiler-cli/ngcc/src/constants.ts

@@ -7,3 +7,4 @@
  */
 
 export const IMPORT_PREFIX = 'ɵngcc';
+export const NGCC_TIMED_OUT_EXIT_CODE = 177;

packages/compiler-cli/ngcc/src/locking/async_locker.ts

@@ -5,9 +5,15 @@
  * Use of this source code is governed by an MIT-style license that can be
  * found in the LICENSE file at https://angular.io/license
  */
+import {NGCC_TIMED_OUT_EXIT_CODE} from '../constants';
 import {Logger} from '../logging/logger';
+
 import {LockFile} from './lock_file';
 
+class TimeoutError extends Error {
+  code = NGCC_TIMED_OUT_EXIT_CODE;
+}
+
 /**
  * AsyncLocker is used to prevent more than one instance of ngcc executing at the same time,
  * when being called in an asynchronous context.
@@ -61,7 +67,7 @@ export class AsyncLocker {
       }
     }
     // If we fall out of the loop then we ran out of rety attempts
-    throw new Error(
+    throw new TimeoutError(
         `Timed out waiting ${
             this.retryAttempts * this.retryDelay /
             1000}s for another ngcc process, with id ${pid}, to complete.\n` +