OZG-4949 OZG-5136 Show error message if form invalid invalid

alfa-client/libs/admin-settings/src/lib/postfach/postfach-container/postfach-form/postfach-form.component.html

 <form class="form flex-col" [formGroup]="formService.form">
   <h1 class="text-2xl font-bold">Absender</h1>
   <p id="absender-desc" class="p-1">Hinterlegen Sie Absenderinformationen zu Ihrem Postfach.</p>
-	<div [formGroupName]="PostfachFormService.ASBSENDER_GROUP" aria-describedby="absender-desc"
-		 class="grid-col-1 mb-2 mt-2 grid w-96 gap-1">
+	<div
+		[formGroupName]="PostfachFormService.ASBSENDER_GROUP"
+		aria-describedby="absender-desc"
+		class="grid-col-1 mb-2 mt-2 grid w-96 gap-1"
+	>
     <text-field
 		data-test-id="absender-name"
       label="Name"
@@ -46,4 +49,7 @@
   >
     Speichern
   </button>
+	<span *ngIf="formService.invalidEmpty" class="text-red-500 m-2"
+	>*Es müssen alle Felder ausgefüllt sein.</span
+	>
 </form>

alfa-client/libs/tech-shared/src/lib/service/formservice.abstract.ts

@@ -124,4 +124,8 @@ export abstract class AbstractFormService {
   public isPatch(): boolean {
     return !isNil(this.source);
   }
+
+  public get invalidEmpty(): boolean {
+    return this.form.invalid;
+  }
 }