update comment

Author: MarcoGorelli

pandas/core/indexing.py

@@ -2130,7 +2130,7 @@ def _setitem_single_column(self, loc: int, value, plane_indexer) -> None:
                 dtype = self.obj.dtypes.iloc[loc]
                 if dtype not in (np.void, object) and not self.obj.empty:
                     # - Exclude np.void, as that is a special case for expansion.
-                    #   We want to warn for
+                    #   We want to raise for
                     #       df = pd.DataFrame({'a': [1, 2]})
                     #       df.loc[:, 'a'] = .3
                     #   but not for