Locale not found throw fatal error

[marcoschivoesse]

Describe the bug
If the store has locale not included in "en-GB", "de-DE", the install process will fail

To Reproduce
Steps to reproduce the behavior:

1. Enable multiple locale different from en-GB and de-DE
2. Install the plugin
3. Result will be an error: [/0/translations/2fbb5fe2e29a4d70aa5854ce7ce3e20b/name] Questo valore non dovrebbe essere vuoto.

Expected behavior
The plugin install correctly

Screenshots

Additional context
The problems are in method getName and getDescription of each method: if the locale isn't en-GB or de-DE, the result will be null and cannot be. Must be return a string.