Set the value of file input in Angular 6

I am using Angular 6 and I want to get the image that is dropped in a div and set it as a value in the input type="file" of a form.

So, the user drops an image in the div, the file input gets that image as a value and then I can submit the form.

This is the code

<form [formGroup]="imageUpload" (ngSubmit)="imageUploadSubmitted()">
  <div id="imageDrop" (drop)="drop($event)" (dragover)="allowDrop($event)" #imageDrop></div> 

  <input type="file" formControlName="imageInput" required #imageInput id="imageInput"  >
  <label>
    <input type="text" formControlName="imageName" placeholder="name" required >
  </label>                      

  <button type="submit" [disabled]="!imageUpload.valid">Submit</button>
</form>

and the component is

  allowDrop(e) {
    e.preventDefault();
  }

  drop(e) {
    e.preventDefault();  
    this.imageUpload.controls.imageInput.reset();  
    this.imageDrop.innerHTML="";    
    let input = this.imageUpload.controls.imageInput as any;
    input.value = e.dataTransfer.files[0];  
    this.readfiles(e.dataTransfer.files);
  }

  readfiles(files){
    const reader = new FileReader();
    let image = new Image();
    reader.onload =  (event) =>{
      this.imageDrop.nativeElement.innerHTML="";                
      let fileReader = event.target as FileReader;
      image.src = fileReader.result;
      image.width = 150; 
      this.imageDrop.nativeElement.appendChild(image);  
      /*if (this.imageUpload.controls.imageInput.value==null) {                
        let input = this.imageUpload.controls.imageInput as any;        
        input.value = event.target.result;  
      }  */
    };
    reader.readAsDataURL(files[0]);    

  }

The input.value in the drop always has a value, but I guess is the wrog type of value. The submit button of the form is not active.

Then maybe I need to read the image to set it as a value, so I will transfer the logic in the readfiles - check the commented out code. This does not work, since I get an error no the result of the input.value = event.target.result; . The error is Property result does not exist on type EventTarget

How can I fix this and set the image as a file input value ?

Thanks

PS, here is the stackblitz