title: failed to set the 'value' property on 'HTMLInputElement' in reactive form
body: <p>In the form of a data record, I upload a picture, the image will be uploaded to a server folder and its name will be stored in the database.</p>
  
  <p>in this editing form i get the file name from server and i need to fill <code>&lt;input type="file"&gt;</code> in this form . using the reactive form in angular6 . </p>
  
  <p>this is my code in ts file : </p>
  
  <pre><code>   ngOnInit() {
    this.EditForm=this.fb.group({
    imageName:['',Validators.compose([Validators.required])]
  })
  this.SetForm(this.dat)
  }
  
    SetForm(dt:data){
     this.EditForm.setValue({imageName:[dt.imageName]});
    }
  </code></pre>
  
  <p>in html : </p>
  
  <pre><code>&lt;form [formGroup]="EditForm"&gt;
      &lt;input type="file" #file formControlName="imageName"&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>and this is my code : <a href="https://stackblitz.com/edit/angular-tcstxf?file=src%2Fapp%2Fapp.component.html" rel="nofollow noreferrer">stackblitz</a></p>
  
  <p>i not idea for this problem , and i have 3 days have problem , please see my code and change that for solve this problem . </p>