[FEATURE]: Missing key commands ought not be fatal errors.

[ariane-emory]

Feature hasn't been suggested before.

• [x] I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

Currently, if a user's configuration file has a keybinding for a non-existent command, it is a fatal error, preventing open code from starting up. This can be very inconvenient when working on features involving new key commands, as one has to switch configuration branches frequently to maintain compatibility with the code's branch.

Missing key commands ought to be a non-fatal error. Instead of just failing to start if a non-existent key command is used in a keybinding in the configuration, a more appropriate solution would be to start normally but bind the key to some function that displays a toast like "No command 'fake_command'" when the key is struck.