Workaround to support ?? operator

See https://github.com/webpack/webpack/issues/10227

frontend/tsconfig.json

 {
   "compilerOptions": {
-    "target": "esnext",
+    "target": "es2018",
     "module": "esnext",
     "strict": true,
     "jsx": "preserve",
@@ -39,4 +39,4 @@
   "exclude": [
     "node_modules"
   ]
-}
+}
\ No newline at end of file