Ensures message is sent w/ sync-done & error events

[DougReeder]

sync-done should always pass a message object with a boolean completed property.

error should always pass an Error object as the message.

This PR complements remotestorage/remotestorage-widget#147

[Copilot]

Pull request overview

This PR standardizes emitted event payloads to match the documented/public API expectations: sync-done should always provide a { completed: boolean } result object, and error should always provide an Error instance.

Changes:

• Ensure Dropbox sync failure path emits sync-done with { completed: false }.
• Ensure IndexedDB database-level errors emit an Error object instead of a non-error/empty payload.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/indexeddb.ts	Updates IndexedDB db.onerror handler to emit an Error instance for error events.
src/dropbox.ts	Updates Dropbox sync hook to emit sync-done with { completed: false } on fetchDelta failure.

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[Copilot]

The emitted Error message here is likely not very actionable: for IndexedDB onerror events, evt.type will usually just be "error". Consider extracting the underlying IndexedDB error (e.g., from evt.target.error / evt.target.error.message when available) so consumers get a meaningful error message while still receiving an Error instance.

Suggested change

	(db as any).onerror = evt => {
	remoteStorage._emit('error', new Error(`database error: ${evt?.type}`));
	(db as any).onerror = (evt: any) => {
	const idbError = evt && evt.target && (evt.target as any).error;
	const detail =
	(idbError && (idbError.message || String(idbError))) ||
	(evt && evt.type) ||
	'unknown';
	remoteStorage._emit('error', new Error(`database error: ${detail}`));

[DougReeder]

This is a good idea, but extracting the error from the event should be in a helper function.

Again, I think we need an IDB test harness for Mocha before we can write a test for this.

[raucao]

OK, sure, but the code suggestion would still improve the error message, no?

Could you create a new issue for the test harness you envision?

[silverbucket]

@DougReeder I activated a copilot review for you to address or ignore as you see fit! I will try to review soon