Fixed issue where Extend Script option would show up even without script attached to the node

(cherry picked from commit dc361d32014c3eab0b80a8422d1f850f854b7532)

editor/editor_resource_picker.cpp

@@ -873,7 +873,12 @@ void EditorScriptPicker::set_create_options(Object *p_menu_node) {
 	}
 
 	menu_node->add_icon_item(get_icon("ScriptCreate", "EditorIcons"), TTR("New Script"), OBJ_MENU_NEW_SCRIPT);
-	menu_node->add_icon_item(get_icon("ScriptExtend", "EditorIcons"), TTR("Extend Script"), OBJ_MENU_EXTEND_SCRIPT);
+	if (script_owner) {
+		Ref<Script> script = script_owner->get_script();
+		if (script.is_valid()) {
+			menu_node->add_icon_item(get_icon("ScriptExtend", "EditorIcons"), TTR("Extend Script"), OBJ_MENU_EXTEND_SCRIPT);
+		}
+	}
 	menu_node->add_separator();
 }