Add handling of a server error for the info endpoint

src/app/login/login.component.ts

@@ -20,6 +20,9 @@ export class LoginComponent {
   ) {
       this.userService.getIdPPreference().subscribe(
         (allAuthInfo: AllAuthInfo) => {
+          if (allAuthInfo === null) {
+            return;
+          }
           this.idps = allAuthInfo.idps;
           this.selectedIdP = allAuthInfo.selected;
         }

src/app/user.service.ts

@@ -35,6 +35,12 @@ export class UserService {
     this.cookieService.set(environment.idpCookieName, String(idp.id));
   }
 
+  public errorHandler(error: any): void {
+    if (error.status === 500) {
+      this.snackBar.open('Server Error');
+    }
+  }
+
   public getIdPPreference(): Observable<AllAuthInfo> {
     let idpID = Number(this.cookieService.get(environment.idpCookieName));
 
@@ -55,6 +61,11 @@ export class UserService {
           selected: selected,
         };
       }
+    ).catch(
+      (error: any) => {
+        this.errorHandler(error);
+        return Observable.of(null);
+      }
     );
   }