GREG-232: Fixing wrong error message

An identity check is attempted for passport IDs for UiB, but this is not supported, and the confirmation dialog shown in this case is wrong. Look at the screenshot for the issue in Jira to see how it looks.

iga/uib.py

@@ -20,7 +20,7 @@ class UibSebra(IgaImplementation):
     ) -> Optional[IgaPerson]:
         search = self.idtype_methodmap.get(id_type)
         if not search:
-            return []
+            return None
         user: User = search(extid)
         if not user:
             return None