Error if keyboard shortcut used for unavailable format

[rlivsey]

Given an editor setup with just bold format available:

new Quill(".editor", {
  formats: ['bold']
});

If a user hits the shortcut for italic then it fails because @editor.doc.formats[name] is undefined here:

Does this need a check for whether or not the format is available, or should Keyboard even be bound to the hotkey if it's not available?