fix comment

Author: h-vetinari

pandas/core/strings.py

@@ -2323,7 +2323,7 @@ def _legal_dtype(series):
         union_mask = np.logical_or.reduce(na_masks, axis=0)
 
         # if there are any non-string, non-null values hidden within an object
-        # dtype, cat_core will fail; catch error and return better error.
+        # dtype, cat_core will fail; catch error and return with better message
         try:
             if na_rep is None and union_mask.any():
                 # no na_rep means NaNs for all rows where any column has a NaN