src/app/components/mitarbeiter-form/mitarbeiter-form.component.ts

@@ -82,6 +82,9 @@ export class MitarbeiterFormComponent {
 
   addSkill() {
     const id = Number(this.mitarbeiterForm.get("newSkill")?.value);
+    if (!id) {
+      return;
+    }
     this.allSkills.subscribe(skills => {
       const newSkill = skills.filter(skill => skill.id == id)[0];
       this.mitarbeiter.skillSet?.push(newSkill);

src/app/components/qualifikation-form/qualifikation-form.component.ts

@@ -55,6 +55,9 @@ export class QualifikationFormComponent {
 
   addEmployee() {
     const employeeId = Number(this.skillForm.get("newEmployee")?.value);
+    if (!employeeId) {
+      return;
+    }
     const employee = this.addableEmployees.find(emp => emp.id === employeeId);
 
     if (employee) {