New error code for a missing AES key

[robinkrahl]

Currently, the PWS commands return an AES decryption failed error if the AES key could not be decrypted. It would be helpful to have a separate error code for the case when no AES key is present (i. e. a factory reset has been performed) to show a helpful error message to the user.

This also applies to the Storage – should I open a second issue for that?

[szszszsz]

I will link it, thank you!