title: Ionic 3 - All imports are unused warning (even though they are being used)
body: <p>I am getting the following error when trying to run a prod build using the following</p>
  
  <blockquote>
    <p>ionic cordova build browser --prod</p>
  </blockquote>
  
  <p>Getting  lot of warnings in the terminal like </p>
  
  <blockquote>
    <p>FormBuilder is declared but never used</p>
  </blockquote>
  
  <p>Even though in my code I am importing it and using it e.g.</p>
  
  <pre><code>import { Validators, FormGroup, FormBuilder } from '@angular/forms';
  
  public form: FormGroup;
  
  constructor(
      private formBuilder: FormBuilder
    ) {
  
  setForm(){
      this.form = this.formBuilder.group({
        password: ['', Validators.required],
        password2: ['', Validators.required]
      });
    }
  </code></pre>
  
  <p>Has anyone had a similar problem? My guess it would be something to do with an npm package update.</p>
  
  <p>Any advice would be great.</p>
  
  <p>Thanks!</p>