angular/projects/ng-devtools/src/lib/devtools.component.html

<ng-container *ngIf="angularExists === true; else errorOrLoad">
  <div class="devtools-wrapper noselect">
    <ng-devtools-tabs [messageBus]="messageBus"></ng-devtools-tabs>
  </div>
</ng-container>
<ng-template #errorOrLoad>
  <ng-container *ngIf="angularExists === false; else load">
    <div>
      Not an Angular app
    </div>
  </ng-container>
  <ng-template #load>
    <div *ngIf="angularExists === null">
      Initializing...
    </div>
  </ng-template>
</ng-template>