Fixes #725

- Delete session entries for objects that no longer exist in Blender

molecularnodes/handlers.py

@@ -35,6 +35,7 @@ def _selection_update_trajectories(self, context: bpy.types.Context) -> None:
 def update_entities(scene):
     "Call the `set_frame()` method of all entities in the current session"
     session = scene.MNSession
+    session.prune()
     for entity in session.entities.values():
         # use the updated method if it exists but otherwise fallback on the old method
         # of updating the trajectories

molecularnodes/session.py

@@ -6,7 +6,7 @@
 from bpy.app.handlers import persistent
 from bpy.props import StringProperty
 from bpy.types import Context
-from databpy.object import get_from_uuid
+from databpy.object import get_from_uuid, LinkedObjectError
 
 from .entities.ensemble.base import Ensemble
 from .entities.molecule.molecule import Molecule
@@ -92,6 +92,16 @@ def get_object(self, uuid: str) -> bpy.types.Object | None:
     def get(self, uuid: str) -> Union[Molecule, Trajectory, Ensemble] | None:
         return self.entities.get(uuid)
 
+    def prune(self) -> None:
+        """
+        Remove any entities that no longer exist in Blender
+        """
+        for uuid in list(self.entities):
+            try:
+                _ = self.entities[uuid].name
+            except LinkedObjectError:
+                del self.entities[uuid]
+
     @property
     def n_items(self) -> int:
         "The number of items being tracked by this session."