Fix compile error for ng dev

frontend/src/environments/environment.ts

@@ -1,6 +1,7 @@
 // This file can be replaced during build by using the `fileReplacements` array.
 // `ng build` replaces `environment.ts` with `environment.prod.ts`.
 // The list of file replacements can be found in `angular.json`.
+declare var require: any;
 
 export const environment = {
     production: false,