fix custom component init (#4123)

reflex/custom_components/custom_components.py

@@ -260,7 +260,7 @@ def _validate_library_name(library_name: str | None) -> NameVariants:
     # Module name is the snake case.
     module_name = "_".join(name_parts)
 
-    custom_component_module_dir = f"reflex_{module_name}"
+    custom_component_module_dir = Path(f"reflex_{module_name}")
     console.debug(f"Custom component source directory: {custom_component_module_dir}")
 
     # Use the same name for the directory and the app.