Some translations are not possible

[leandroalbero]

Issue description

Running latest image easynmt/api:2.0-cpu with the model set to m2m_100_418M and english as target language fails for some translations. Here are some examples:

• 'imagina a mi'
• 'imagina un sol'
• 'imagina a un vikingo'

In this case for example, setting the source_lang to 'es' fixed the issue, so maybe the problem is somewhere in the language detection step or that there isn't a translation direction from the detected language to english.

Docker logs output:

[2023-09-28 08:38:08 +0000] [60] [INFO] Waiting for application startup.
[2023-09-28 08:38:08 +0000] [60] [INFO] Application startup complete.
Exception: 'jbo'

the text of the exception varies with every prompt, I guess it is the code of the detected language