Hi,
I had this problem running the evaluation on Colab. Any ideas?

***** Running Evaluation *****
Num examples = 21018
Batch size = 64
[329/329 21:25]
TypeError                                 Traceback (most recent call last)
 in ()
----> 1 trainer.evaluate(max_length=max_target_length)
2 frames
/usr/local/lib/python3.7/dist-packages/transformers/trainer.py in evaluation_loop(self, dataloader, description, prediction_loss_only, ignore_keys, metric_key_prefix)
2407
2408         if all_losses is not None:
 → 2409             metrics[f"{metric_key_prefix}loss"] = all_losses.mean().item()
2410
2411         # Prefix all keys with metric_key_prefix + '’
TypeError: ‘NoneType’ object does not support item assignment