restrict_to_submodel in TRAMDataset

https://github.com/deeptime-ml/deeptime/blob/f4ae6e4ca6706ec6fa9988acf8c80528263ba9d9/deeptime/markov/msm/tram/_tram_dataset.py#L329C3-L356C29

I think in line 334, for k in range(self.n_therm_states), it would not work unless len(dtrajs)==n_therm_states.

Is this correct?