Add missing word to text of the alert dialog

editor/editor_node.cpp

@@ -1411,7 +1411,7 @@ void EditorNode::_dialog_display_load_error(String p_file, Error p_error) {
 				show_accept(vformat(TTR("Scene file '%s' appears to be invalid/corrupt."), p_file.get_file()), TTR("OK"));
 			} break;
 			case ERR_FILE_NOT_FOUND: {
-				show_accept(vformat(TTR("Missing file '%s' or one its dependencies."), p_file.get_file()), TTR("OK"));
+				show_accept(vformat(TTR("Missing file '%s' or one of its dependencies."), p_file.get_file()), TTR("OK"));
 			} break;
 			default: {
 				show_accept(vformat(TTR("Error while loading file '%s'."), p_file.get_file()), TTR("OK"));