file_upload replays stale error on identical-argument retries

file_upload caches error results by argument identity: retrying a failed call with the exact same paths/ref/tabId replays the same error forever ("expected array, received undefined"), even though the array is well-formed. Changing just the filename in paths makes the retry succeed instantly. Confirmed by direct testing — same args = same error every time; any tiny arg change = real execution. Looks like a stale-result cache, not a serialization bug.

Workaround: vary the arguments (e.g. rename the temp file) on retry instead of resending the same call.