Crash when selecting statistic type in label splitter if items haven't been labelled

[OllyK]

Unable to open file in 'objects' directory as it doesn't exist:

.Traceback (most recent call last): File "/scratch/olly/SuRVoS/survos/widgets/label_partitioning.py", line 310, in on_feature_changed self.show_stats(stype=stype) File "/scratch/olly/SuRVoS/survos/widgets/label_partitioning.py", line 356, in show_stats self.feature = self.DM.load_ds('objects/{}'.format(stype)) File "/scratch/olly/SuRVoS/survos/core/model.py", line 188, in load_ds