FIX: problem when importance keyword was not present in diff output

src/caosdb/apiutils.py

@@ -726,8 +726,13 @@ def merge_entities(entity_a: Entity, entity_b: Entity):
 
     for key in diff_r2["properties"]:
         if key in diff_r1["properties"]:
-            if (diff_r1["properties"][key]["importance"] !=
-                diff_r2["properties"][key]["importance"]):
+            if ("importance" in diff_r1["properties"][key] and
+                "importance" in diff_r2["properties"][key]):
+                if (diff_r1["properties"][key]["importance"] !=
+                    diff_r2["properties"][key]["importance"]):
+                    raise NotImplementedError()
+            elif ("importance" in diff_r1["properties"][key] or
+                  "importance" in diff_r2["properties"][key]):
                 raise NotImplementedError()
             
             for attribute in ("datatype", "unit", "value"):