github · manuelpuyol · May 19, 2025 · May 19, 2025 · May 19, 2025 · May 19, 2025
@@ -220,10 +220,10 @@ export class IncludeFragmentElement extends HTMLElement {
   }
 
   // Functional stand in for the W3 spec "queue a task" paradigm
-  async #task(eventsToDispatch: string[]): Promise<void> {
+  async #task(eventsToDispatch: string[], error?: Error): Promise<void> {
     await new Promise(resolve => setTimeout(resolve, 0))
     for (const eventType of eventsToDispatch) {
-      this.dispatchEvent(new Event(eventType))
+      this.dispatchEvent(error ? new CustomEvent(eventType, {detail: {error}}) : new Event(eventType))
     }
   }
 
@@ -258,7 +258,7 @@ export class IncludeFragmentElement extends HTMLElement {
       // Dispatch `error` and `loadend` async to allow
       // the `load()` promise to resolve _before_ these
       // events are fired.
-      this.#task(['error', 'loadend'])
+      this.#task(['error', 'loadend'], error as Error)
       throw error
     }
   }

@@ -342,6 +342,8 @@ suite('include-fragment-element', function () {
     const event = await when(div.firstChild, 'error')
     assert.equal(event.bubbles, false)
     assert.equal(event.cancelable, false)
+    assert.instanceOf(event.detail.error, Error)
+    assert.equal(event.detail.error.message, 'Failed to load resource: the server responded with a status of 500')
   })
 
   test('adds is-error class on 500 status', async function () {