fix: check class of dataloader before blindly calling _finish() (#1850)

nnunetv2/training/nnUNetTrainer/nnUNetTrainer.py

@@ -11,6 +11,8 @@
 
 import numpy as np
 import torch
+from batchgenerators.dataloading.multi_threaded_augmenter import MultiThreadedAugmenter
+from batchgenerators.dataloading.nondet_multi_threaded_augmenter import NonDetMultiThreadedAugmenter
 from batchgenerators.dataloading.single_threaded_augmenter import SingleThreadedAugmenter
 from batchgenerators.transforms.abstract_transforms import AbstractTransform, Compose
 from batchgenerators.transforms.color_transforms import BrightnessMultiplicativeTransform, \
@@ -865,9 +867,11 @@ def on_train_end(self):
         old_stdout = sys.stdout
         with open(os.devnull, 'w') as f:
             sys.stdout = f
-            if self.dataloader_train is not None:
+            if self.dataloader_train is not None and \
+                    isinstance(self.dataloader_train, (NonDetMultiThreadedAugmenter, MultiThreadedAugmenter)):
                 self.dataloader_train._finish()
-            if self.dataloader_val is not None:
+            if self.dataloader_val is not None and \
+                    isinstance(self.dataloader_train, (NonDetMultiThreadedAugmenter, MultiThreadedAugmenter)):
                 self.dataloader_val._finish()
             sys.stdout = old_stdout