message: Check if MimeType is set, to prevent hard error in CourseEdit
diff: @@ -171,6 +171,10 @@ export class CourseMediaComponent implements OnInit {
  }
  getSimpleMimeType(file: IFile): string {
  + if (file.mimeType === undefined) {
  + return 'unknown';
  + }
  +
  const mimeType = file.mimeType.toLowerCase();
  const archives = [
  'application/x-bzip',
  