add blocking state to make dealing with log in errors more user friendly

src/app/core/auth/auth-blocking.guard.ts

@@ -0,0 +1,31 @@
+import { Injectable } from '@angular/core';
+import { CanActivate } from '@angular/router';
+import { select, Store } from '@ngrx/store';
+import { Observable } from 'rxjs';
+import { distinctUntilChanged, filter, map, take, tap } from 'rxjs/operators';
+import { AppState } from '../../app.reducer';
+import { isAuthenticationBlocking } from './selectors';
+
+/**
+ * A guard that blocks the loading of any
+ * route until the authentication status has loaded.
+ * To ensure all rest requests get the correct auth header.
+ */
+@Injectable({
+  providedIn: 'root'
+})
+export class AuthBlockingGuard implements CanActivate {
+
+  constructor(private store: Store<AppState>) {
+  }
+
+  canActivate(): Observable<boolean> {
+    return this.store.pipe(select(isAuthenticationBlocking)).pipe(
+      map((isBlocking: boolean) => isBlocking === false),
+      distinctUntilChanged(),
+      filter((finished: boolean) => finished === true),
+      take(1),
+    );
+  }
+
+}