Defer `ActionMapEditor::_action_edited` signal to prevent tree updates when tree is blocked.

editor/action_map_editor.cpp

@@ -428,6 +428,7 @@ void ActionMapEditor::update_action_list(const Vector<ActionInfo> &p_action_info
 		// Update Tree...
 
 		TreeItem *action_item = action_tree->create_item(root);
+		ERR_FAIL_NULL(action_item);
 		action_item->set_meta("__action", action_info.action);
 		action_item->set_meta("__name", action_info.name);
 
@@ -604,7 +605,7 @@ ActionMapEditor::ActionMapEditor() {
 	action_tree->set_column_custom_minimum_width(1, 80 * EDSCALE);
 	action_tree->set_column_expand(2, false);
 	action_tree->set_column_custom_minimum_width(2, 50 * EDSCALE);
-	action_tree->connect("item_edited", callable_mp(this, &ActionMapEditor::_action_edited));
+	action_tree->connect("item_edited", callable_mp(this, &ActionMapEditor::_action_edited), CONNECT_DEFERRED);
 	action_tree->connect("item_activated", callable_mp(this, &ActionMapEditor::_tree_item_activated));
 	action_tree->connect("button_clicked", callable_mp(this, &ActionMapEditor::_tree_button_pressed));
 	main_vbox->add_child(action_tree);