undo: pvs/v547

buf is nonnull when xfree(buf) is executed.

free(NULL) is safe (for target compilers) so xfree(NULL) is also safe.

src/nvim/undo.c

@@ -1018,9 +1018,7 @@ static ExtmarkUndoObject *unserialize_extmark(bufinfo_T *bi, bool *error,
       goto error;
   }
 
-  if (buf) {
   xfree(buf);
-  }
 
   return extup;