message: Remove Error-Case 401 (when user does not have permission to view this course a 404 is triggered)
  Show err.error.message instead err.message
  Migrate to SnackBarService
diff: @@ -7,6 +7,7 @@ import {UserService} from '../../shared/services/user.service';
  import {IUser} from '../../../../../../shared/models/IUser';
  import {User} from '../../models/User';
  import {MatSnackBar, MatDialog} from '@angular/material';
  +import {SnackBarService} from '../../shared/services/snack-bar.service';
  import {DownloadCourseDialogComponent} from './download-course-dialog/download-course-dialog.component';
  import {TitleService} from '../../shared/services/title.service';
  import {LastVisitedCourseContainerUpdater} from '../../shared/utils/LastVisitedCourseContainerUpdater';
  @@ -27,7 +28,7 @@ export class CourseDetailComponent implements OnInit {
  private route: ActivatedRoute,
  private courseService: CourseService,
  public userService: UserService,
  - private snackBar: MatSnackBar,
  + private snackBar: SnackBarService,
  private dialog: MatDialog,
  private titleService: TitleService,
  private userDataService: UserDataService,
  @@ -47,14 +48,12 @@ export class CourseDetailComponent implements OnInit {
  this.course = await this.courseService.readCourseToView(courseId);
  this.titleService.setTitleCut(['Course: ', this.course.name]);
  LastVisitedCourseContainerUpdater.addCourseToLastVisitedCourses(courseId, this.userService, this.userDataService);
  - } catch (errorResponse) {
  - if (errorResponse.status === 401) {
  - this.snackBar.open('You are not authorized to view this course.', '', {duration: 3000});
  - } else if (errorResponse.status === 404) {
  - this.snackBar.open('Your selected course is not available.', '', {duration: 3000});
  + } catch (err) {
  + if (err.status === 404) {
  + this.snackBar.open('Your selected course is not available.');
  this.router.navigate(['/not-found']);
  } else {
  - this.snackBar.open('Something went wrong: ' + errorResponse.message, '', {duration: 3000});
  + this.snackBar.open('Something went wrong: ' + err.error.message);
  }
  }
  }
  