Prevent username retrieval if user is not authenticated and fix variable naming in DiscordAppealMapper.

frontend/src/app/services/auth.service.ts

@@ -53,6 +53,9 @@ export class AuthService {
       console.log("Reloading username for localhost");
       this._username.set('developer');
     }
+    if (!this.isAuthenticated$()) {
+      return;
+    }
     this.loginService.getUsername().subscribe({
       next: (username) => {
         console.log("Username retrieved: " + username.username);