Confirming OpenPGP with a wrong key oops with no output

When confirming an openpgp key if the user inputs text signed with an incorrect key launchpad just oops.

I was able to analyze the oops (https://oops.canonical.com/?oopsid=OOPS-cde01264bb18e3c177d06fe2ed81fce4) and found the key id was different from the one I was trying to confirm:
```
lp.services.gpg.interfaces.GPGKeyTemporarilyNotFoundError: GPG key D38C33334F9E8757 not found due to a server or network failure.
```

It would be useful for an end-user to receive a message error indicating the error "Key XXXXXXX not found".