Proper exception when language does not exist

Hello,

Running Ubuntu 22.10.

Just installed with "pip3 install vosk".
Created the test_ffmpeg.py exact copy of the current one : https://github.com/alphacep/vosk-api/blob/master/python/example/test_ffmpeg.py.
When trying command python3 test_ffmpeg.py myvideo.mkv, it runs perfectly.

I have tried to put the French model in the directory where test_ffmpeg.py is (as in the video of the installation page / website).
Both with renaming as "model" or with its original name ("vosk-model-fr-0.22").
When running the command, it does not use the French model.
So I edited test_ffmpeg.py and changer en-us => fr-fr (line 12)
When trying the command again, I get this error message:
```
lang fr-fr does not exist
Exception ignored in:
Traceback (most recent call last):
File "/home/marc/.local/lib/python3.10/site-packages/vosk/__init__.py", line 60, in __del__
_c.vosk_model_free(self._handle)
AttributeError: 'Model' object has no attribute '_handle'
```
Can you help please?

Regards,
Marc