fixup! improve push performance scaling

Author: ilia-kats

src/mudata/_core/mudata.py

@@ -2331,13 +2331,13 @@ def _push_attr(
             # reorder global DF to conform to modality order
             idx = np.empty(mod_n_attr, dtype=mod_map.dtype)
             idx[mod_map[mask] - 1] = np.arange(mod_n_attr)
-            df = df.iloc[idx].set_index(np.arange(mod_n_attr))
+            df = df.iloc[idx].set_index(np.arange(mod_n_attr, dtype=mod_map.dtype))
 
             if not only_drop:
                 # TODO: _maybe_coerce_to_bool
                 # TODO: _maybe_coerce_to_int
                 # TODO: _prune_unused_categories
-                mod_df = getattr(mod, attr).set_index(np.arange(mod_n_attr, dtype=mod_map.dtype))
+                mod_df = getattr(mod, attr).set_index(np.arange(mod_n_attr))
                 mod_df = _update_and_concat(mod_df, df)
                 mod_df = mod_df.set_index(getattr(mod, f"{attr}_names"))
                 setattr(mod, attr, mod_df)