Fix bug on empty delete in merge table

CHANGELOG.md

@@ -16,6 +16,8 @@
 - Prioritize datajoint filepath entry for defining abs_path of analysis nwbfile
     #918
 - Fix potential duplicate entries in Merge part tables #922
+- Add logging of AnalysisNwbfile creation time and size #937
+- Fix error on empty delete call in merge table. #940
 - Add log of AnalysisNwbfile creation time, size, and access count #937, #941
 
 ### Pipelines

src/spyglass/utils/dj_merge_tables.py

@@ -799,11 +799,16 @@ def merge_populate(self, source: str, keys=None):
 
     def delete(self, force_permission=False, *args, **kwargs):
         """Alias for cautious_delete, overwrites datajoint.table.Table.delete"""
-        for part in self.merge_get_part(
-            restriction=self.restriction,
-            multi_source=True,
-            return_empties=False,
+        if not (
+            parts := self.merge_get_part(
+                restriction=self.restriction,
+                multi_source=True,
+                return_empties=False,
+            )
         ):
+            return
+
+        for part in parts:
             part.delete(force_permission=force_permission, *args, **kwargs)
 
     def super_delete(self, warn=True, *args, **kwargs):