tatoeba_mt: File not found error and key error
Looks like I solved my problems ...
## Dataset viewer issue for 'tatoeba_mt'

**Link:** https://huggingface.co/datasets/Helsinki-NLP/tatoeba_mt

My data loader script does not seem to work.
The files are part of the local repository but cannot be found. An example where it should work is the subset for "afr-eng".

Another problem is that I do not have validation data for all subsets and I don't know how to properly check whether validation exists in the configuration before I try to download it. An example is the subset for "afr-deu".

Am I the one who added this dataset ? Yes
