feat(ext/web): Add error events for event listener and timer errors (#14159)

- feat: Add handleable error event for even listener errors
- feat: Add handleable error event for setTimeout()/setInterval() errors
- feat: Add Deno.core.destructureError()
- feat: Add Deno.core.terminate()
- fix: Don't throw listener errors from dispatchEvent()
- fix: Use biased mode when selecting between mod_evaluate() and
  run_event_loop() results

1 files changed, 8 insertions, 6 deletions

diff --git a/runtime/js/11_workers.js b/runtime/js/11_workers.js
index 80e85a3a1..5b8d03e71 100644
--- a/runtime/js/11_workers.js
+++ b/runtime/js/11_workers.js
@@ -140,14 +140,16 @@
         error: null,
       });
 
-      let handled = false;
-
       this.dispatchEvent(event);
-      if (event.defaultPrevented) {
-        handled = true;
+      // Don't bubble error event to window for loader errors (`!e.fileName`).
+      // TODO(nayeemrmn): Currently these are never bubbled because worker
+      // error event fields aren't populated correctly and `e.fileName` is
+      // always empty.
+      if (e.fileName && !event.defaultPrevented) {
+        window.dispatchEvent(event);
       }
 
-      return handled;
+      return event.defaultPrevented;
     }
 
     #pollControl = async () => {
@@ -165,7 +167,7 @@
           } /* falls through */
           case 2: { // Error
             if (!this.#handleError(data)) {
-              throw new Error("Unhandled error event in child worker.");
+              throw new Error("Unhandled error in child worker.");
             }
             break;
           }