fix: some crashes

music_kraken/objects/collection.py

@@ -60,7 +60,9 @@ class Collection(Generic[T]):
             self._contains_ids.remove(__object.id)
 
         for name, value in self._id_to_index_values[__object.id]:
+            if name in self._indexed_values:
                 del self._indexed_values[name]
+            if value in self._indexed_to_objects:
                 del self._indexed_to_objects[value]
 
         del self._id_to_index_values[__object.id]
@@ -228,7 +230,6 @@ class Collection(Generic[T]):
         else:
             # merge only if the two objects are not the same
             if existing_object.id == __object.id:
-                exit()
                 return
 
             append_to._unmap_element(existing_object)
@@ -282,7 +283,7 @@ class Collection(Generic[T]):
             yield from c.__iter__(finished_ids=finished_ids)
 
     def __merge__(self, __other: Collection, override: bool = False):
-        self.extend(__other.__iter__())
+        self.extend(__other)
 
     def __getitem__(self, item: int):
         if item < len(self._data):

music_kraken/objects/parents.py

@@ -201,10 +201,16 @@ class OuterProxy:
 
         a._inner.__merge__(b._inner, override=override)
         for collection, child_collection in b._inner._is_collection_child.items():
+            try:
                 collection.children.remove(child_collection)
+            except ValueError:
+                pass
             
         for collection, parent_collection in b._inner._is_collection_parent.items():
+            try:
                 collection.parents.remove(parent_collection)
+            except ValueError:
+                pass
 
         a._inner._refers_to_instances.update(b._inner._refers_to_instances)