[BUG] TrainEndCheckpoint not working with LoadInitState

[YannDubs]

I'm trying to use TrainEndCheckpoint with LoadInitState but it's not working. It doesn't even return any error as you are using with suppress(Exception). The suppressed error is *** AttributeError: 'TrainEndCheckpoint' object has no attribute 'f_history_', yet the file exists and self.checkpoint.checkpoint_.f_history_==.../train_end_history.json'.

I think the issue is that TrainEndCheckpoint stopped inheriting from Checkpoint in #463. I.e. it doesn't have a f_history_ attribute anymore. This could be simply resolved by redirecting self.f_history_ to self.checkpoint_.f_history_.

[BenjaminBossan]

Thank you very much for this detailed investigation. We will look into this.