Fix the whole test suite of descriptors.

jedi/evaluate/param.py

@@ -120,7 +120,9 @@ class TreeArguments(AbstractArguments):
                 for values in list(zip_longest(*iterators)):
                     # TODO zip_longest yields None, that means this would raise
                     # an exception?
-                    yield None, context.get_merged_lazy_context(values)
+                    yield None, context.get_merged_lazy_context(
+                        [v for v in values if v is not None]
+                    )
             elif stars == 2:
                 arrays = self._evaluator.eval_element(self.context, el)
                 for dct in arrays: