title: TypeError: Cannot read property 'something' of undefined. Angular 2
body: <p>i have popular error, TypeError: Cannot read property 'something' of undefined. and my code works <br>But why i should to use *ngIf or async? why it happens?<br> and can i solve this problem without this strange solutions what i describe bellow <br>Sorry but i can not find answer why</p>
  
  <pre><code>// service
    public getEmployee(id) {
      return this._af.database.object(`/employee/${id}`)
       .map(response =&gt; response)
       .catch(error =&gt; Observable.throw(error.json()));
    }
  
  
  
  //component
    public employee: Employee;
  
    ngOnInit() {
      this.route.params
        .switchMap((params: Params) =&gt; this._EmployeesService.getEmployee(params['employeeId']))
        .subscribe(employee =&gt; {
          this.employee = employee;
        });
    }
  
  
  //html
  &lt;div *ngIf="employee"&gt;...&lt;/div&gt;` // ok
  &lt;div&gt;{{employee?.name}}&lt;/div&gt; // also  ok
  
  &lt;div&gt;{{employee.name}}&lt;/div&gt; // error here, TypeError: Cannot read property 'name' of undefined.
  </code></pre>