Fix: show errors for select dropdowns (#4979)

src-ui/src/app/components/common/input/select/select.component.html

@@ -9,7 +9,7 @@
       </button>
     </div>
     <div [class.col-md-9]="horizontal">
-      <div [class.input-group]="allowCreateNew || showFilter">
+      <div [class.input-group]="allowCreateNew || showFilter" [class.is-invalid]="error">
         <ng-select name="inputId" [(ngModel)]="value"
           [disabled]="disabled"
           [style.color]="textColor"
@@ -42,6 +42,9 @@
           </svg>
         </button>
       </div>
+      <div class="invalid-feedback">
+        {{error}}
+      </div>
       <small *ngIf="hint" class="form-text text-muted">{{hint}}</small>
       <small *ngIf="getSuggestions().length > 0">
         <span i18n>Suggestions:</span>&nbsp;