Index: frontend/node_modules/array-union/index.js
===================================================================
--- frontend/node_modules/array-union/index.js	(revision 9af201e94b5a79beb92a30858fc54de4bc3b9449)
+++ frontend/node_modules/array-union/index.js	(revision 9af201e94b5a79beb92a30858fc54de4bc3b9449)
@@ -0,0 +1,5 @@
+'use strict';
+
+module.exports = (...arguments_) => {
+	return [...new Set([].concat(...arguments_))];
+};