Fixed check for empty signature

Author: guiyrt

src/diffusers/pipelines/pipeline_utils.py

@@ -1057,7 +1057,7 @@ def get_detailed_type(obj: Any) -> Type:
                 continue
             elif (
                 arg is not None
-                and expected_types[kw] is not inspect.Signature.empty  # no type annotations
+                and not expected_types[kw] == (inspect.Signature.empty,)  # no type annotations
                 and not is_valid_type(arg, expected_types[kw])
             ):
                 logger.warning(f"Expected types for {kw}: {expected_types[kw]}, got {get_detailed_type(arg)}.")