added custom ErrorStateMatcher to show feedback von Password Confirmation

src/app/account/register/password-error-state-matcher.spec.ts

@@ -0,0 +1,7 @@
+import { PasswordErrorStateMatcher } from './password-error-state-matcher';
+
+describe('PasswordErrorStateMatcher', () => {
+  it('should create an instance', () => {
+    expect(new PasswordErrorStateMatcher()).toBeTruthy();
+  });
+});

src/app/account/register/password-error-state-matcher.ts

@@ -0,0 +1,11 @@
+import { ErrorStateMatcher } from '@angular/material/core';
+import { FormControl, FormGroupDirective, NgForm } from '@angular/forms';
+
+export class PasswordErrorStateMatcher implements ErrorStateMatcher {
+  isErrorState(control: FormControl | null, form: FormGroupDirective | NgForm | null): boolean {
+    const invalidControl = !!(control && control.invalid && control.parent.touched);
+    const invalidParent = !!(control && control.parent && control.parent.invalid && control.parent.touched);
+
+    return invalidControl || invalidParent;
+  }
+}