[Bug]: SimpleFIN error not surfaced to UI

### Verified issue does not already exist?

- [x] I have searched and found no existing issue

### What happened?

I recently set up an American Express account through SimpleFIN. The original bank sync of the account seemed to work just fine. However, all subsequent sync attempts are throwing exceptions on the client side JS. This seems to be the offending block in sync.ts:

As you can see, `download` ends up undefined because the account ID is not actually found in the `res` object. This leads to a thrown exception at the highlighted line since it tries to access the `error_code` property on `undefined`.

The result of this is I can't sync this account at all, and also the "sync all" button errors out at this account so I need to sync all of my other accounts manually.

### How can we reproduce the issue?

No clue, I'm guessing it's either a problem with the SimpleFIN data coming back or just a logic bug in the JS. There _should_ be new transactions coming in from this account, though. Let me know if I can give you anything else to help debug.

### Where are you hosting Actual?

Docker

### What browsers are you seeing the problem on?

Chrome

### Operating System

Windows 11

Start in sync.ts at the download lookup shown in the report and trace the SimpleFIN sync response when the account ID is missing. Reproduce with the affected American Express/SimpleFIN account if available, then verify that the sync error is surfaced in the UI without preventing other accounts from syncing.

Scritto dal modello di indicizzazione a partire dal testo della issue.