GridMap: fix next/prev plane text, fix meta not found

modules/gridmap/grid_map_editor_plugin.cpp

@@ -101,8 +101,8 @@ void GridMapEditor::_menu_option(int p_option) {
 			}
 
 			if (edit_axis != new_axis) {
-				int item1 = options->get_popup()->get_item_id(MENU_OPTION_NEXT_LEVEL);
-				int item2 = options->get_popup()->get_item_id(MENU_OPTION_PREV_LEVEL);
+				int item1 = options->get_popup()->get_item_index(MENU_OPTION_NEXT_LEVEL);
+				int item2 = options->get_popup()->get_item_index(MENU_OPTION_PREV_LEVEL);
 				if (edit_axis == Vector3::AXIS_Y) {
 					options->get_popup()->set_item_text(item1, TTR("Next Plane"));
 					options->get_popup()->set_item_text(item2, TTR("Previous Plane"));
@@ -779,7 +779,7 @@ void GridMapEditor::edit(GridMap *p_gridmap) {
 
 	set_process(true);
 
-	Vector3 edited_floor = p_gridmap->get_meta("_editor_floor_");
+	Vector3 edited_floor = p_gridmap->has_meta("_editor_floor_") ? p_gridmap->get_meta("_editor_floor_") : Variant();
 	clip_mode = p_gridmap->has_meta("_editor_clip_") ? ClipMode(p_gridmap->get_meta("_editor_clip_").operator int()) : CLIP_DISABLED;
 
 	for (int i = 0; i < 3; i++) {