DOC: Remove single test todo

unittests/test_error_handling.py

@@ -78,8 +78,6 @@ def test_entity_does_not_exist_error():
     assert isinstance(err, EntityDoesNotExistError)
     assert err.entity.name == ent.name
 
-# TODO: remaining single error tests
-
 
 def test_entity_error():
     """Code 0; most basic."""