Add better onerror handling.

[fungairino]

It seems like in cases where there is no error on the transaction, a generic AbortError is thrown. However if you inspect the error argument (which is not used) you can actually see the real error that was encountered. This is applicable to the "DataError: Failed to read large IndexedDB value" error

See:

idb/src/wrap-idb-value.ts

Lines 85 to 86 in eb2fc14

	const error = () => {
	reject(tx.error || new DOMException('AbortError', 'AbortError'));

The expectation would be that we should see the real cause, and not swallow it.

[fungairino]

Related to this issue, it seems like this Promise also is running into uncaught error calls as well.

Uncaught (in promise) AbortError: AbortError

The stack trace points to the promise created by this line: https://github.com/jakearchibald/idb/blob/main/src/wrap-idb-value.ts#L164

Seems like this needs a similar fix like the one done here where we just catch the rejected error.

(Related issue on uncaught promise errors: #115)

[jakearchibald]

Thanks for reporting. I'll take a look.