fix(images): avoid OSError - to many open files

Closes #145

src/nrtk_explorer/app/images/images.py

@@ -33,7 +33,9 @@ def __init__(self, server):
         )
 
     def _load_image(self, dataset_id: str):
-        return self.server.context.dataset.get_image(int(dataset_id))
+        img = self.server.context.dataset.get_image(int(dataset_id))
+        img.load()  # Avoid OSError(24, 'Too many open files')
+        return img
 
     def get_image(self, dataset_id: str, **kwargs):
         """For cache side effects pass on_add_item and on_clear_item callbacks as kwargs"""