when class_name is empty, it should not be rendered as None

reflex/components/radix/primitives/base.py

@@ -26,7 +26,7 @@ def _render(self) -> Tag:
             ._render()
             .add_props(
                 **{
-                    "class_name": f"{format.to_title_case(self.tag or '')} {self.class_name}",
+                    "class_name": f"{format.to_title_case(self.tag or '')} {self.class_name or ''}",
                 }
             )
         )