message: remove click event
diff: <mat-icon>show_chart</mat-icon>
  </button>
  - <button mat-icon-button (click)="showReport(course._id)"
  - *ngIf="!course.active" disabled>
  + <button mat-icon-button *ngIf="!course.active" disabled>
  <mat-icon color="warn">visibility_off</mat-icon>
  </button>
  