It seems to me that the issue may be that line 207 uses val_set rather than self.val_set - and while val_set is set in the codepaths starting in lines 185 and 190 respectively, it remains unassigned in the "else" codepath starting in line 196.
The offending code was added in this commit about 4 months ago.
Trying to run a minimal pretraining job without specifying a validation set or using forced splits I get an error concerning an unassigned variable:
It seems to me that the issue may be that line 207 uses val_set rather than self.val_set - and while val_set is set in the codepaths starting in lines 185 and 190 respectively, it remains unassigned in the "else" codepath starting in line 196.
The offending code was added in this commit about 4 months ago.