Log unrecognized AstroPay errors at 'error' level
If the error is unfamiliar enough we don't have a user message for
it, we probably want to see it in the 'error' logs, not just warning.
It'll duplicate these messages at both warning and error, but there
should not be too many of them.
Bug: T106053
Change-Id: I4d231743741b35209d50bde0205697230eec4b9a