message: Check existence of model in unit general info form
diff: <textarea matInput formControlName="description" placeholder="Description" rows="4"></textarea>
  </mat-form-field>
  - <mat-form-field *ngIf="model.progressable">
  + <mat-form-field *ngIf="model?.progressable">
  <input matInput formControlName="deadline" [matDatepicker]="deadlineDatepicker" placeholder="Optional deadline">
  <mat-datepicker-toggle matSuffix [for]="deadlineDatepicker"></mat-datepicker-toggle>
  <mat-datepicker #deadlineDatepicker></mat-datepicker>
  