title: Angular Form Array, first Index always null
body: <p>Please assist, i am trying to view data from the component to the view, using angular form array. the following solution: <a href="https://stackoverflow.com/questions/48803725/angular-5-formarray-get-data-from-database-and-show-rows?utm_medium=organic&amp;utm_source=google_rich_qa&amp;utm_campaign=google_rich_qa">Angular 5 FormArray get data from database and show rows</a> .  helped me but now im experiencing a problem where the first index of the form array is always null and im recieving the following errors :</p>
  
  <pre><code>ERROR Error: Cannot find control with path: '[object Object] -&gt; 0'
  at _throwError (forms.js:2432)
  at setUpFormContainer (forms.js:2405)
  at FormGroupDirective.addFormGroup (forms.js:6691)
  at FormGroupName.AbstractFormGroupDirective.ngOnInit (forms.js:2568) 
  ...
  
  Cannot read property 'controls' of undefined
  at Object.eval [as updateDirectives] 
  ...
  </code></pre>
  
  <p>in my ngOnInit i only have the following :</p>
  
  <pre><code>this.SectionForm= this.formBuilder.group({
    sectionData: this.formBuilder.array([this.buildDevelopmentSector()])
  });
  
  this.activatedRoute.params.subscribe(res =&gt;
    // get data and push the data to a formArray called sectionDataArray
    this.GetDataFromApi(res.requestId)
  );
  </code></pre>
  
  <p>the view has the following part :</p>
  
  <pre><code>  &lt;div [formGroup] ="SectionForm"&gt;
      &lt;div [formArrayName]="sectionDataArray"&gt;
        &lt;div *ngFor="let section of sectionDataArray.controls ; let i = index" [formGroupName]="i"&gt;
            ...
            ...
            ...
          &lt;/div&gt;
  </code></pre>
  
  <p>Looking at the logs i see the following :</p>
  
  <pre><code>  0:
       amount:""
       percentage:""
       name:""
       quantity:""
       __proto__:Object 
  
    1:
       amount:1200000
       percentage:23
       name: "Repo"
       quantity:20000
       __proto__:Object
  
    length:2
       __proto__:Array(0)
  </code></pre>