Fix --print_config failing in some cases (#517).

CHANGELOG.rst

@@ -28,6 +28,8 @@ Fixed
 - Parsing incorrectly provides file content when type is a union with a
   subclass, PathLike and string (`#516
   <https://github.com/omni-us/jsonargparse/issues/516>`__).
+- ``--print_config`` failing in some cases (`#517
+  <https://github.com/omni-us/jsonargparse/issues/517>`__).
 
 
 v4.29.0 (2024-05-24)

jsonargparse/_common.py

@@ -122,7 +122,7 @@ def get_unaliased_type(cls):
 def is_dataclass_like(cls) -> bool:
     if is_generic_class(cls):
         return is_dataclass_like(cls.__origin__)
-    if not inspect.isclass(cls):
+    if not inspect.isclass(cls) or cls is object:
         return False
     if is_final_class(cls):
         return True

jsonargparse/_parameter_resolvers.py

@@ -108,7 +108,7 @@ def is_classmethod(parent, component) -> bool:
 
 
 def is_lambda(value: Any) -> bool:
-    return callable(value) and value.__name__ == "<lambda>"
+    return callable(value) and getattr(value, "__name__", "") == "<lambda>"
 
 
 def ast_str(node):