title: Angular: Member <function-name> is not callable
body: <p>I'm assigning an imported function to a component property in the <code>constructor</code> in order to use it in the <code>template</code>. </p>
  
  <p>Builds happen properly, but in my editor (Visual Studio Code with Angular Language Service), the below error is shown.</p>
  
  <p><a href="https://i.stack.imgur.com/1qO7K.png" rel="noreferrer"><img src="https://i.stack.imgur.com/1qO7K.png" alt="Error"></a></p>
  
  <p>Below is the code of my exported function.</p>
  
  <pre><code>export function downloadFile(fileUrl: string, fileName: string) {
      let a = document.createElement('a');
      a.href = fileUrl;
      a.download = fileName;
      a.click();
  }
  </code></pre>
  
  <p>Below is my code in the component.</p>
  
  <pre><code>import { downloadFile } from '../../shared/utilities';
  
  @Component({
      ...
  })
  export class SomeComponent {
      downloadFile: any;
  
      constructor() {
          this.downloadFile = downloadFile;
      }
  }
  </code></pre>
  
  <p>I can't get why this error is shown. Please help!</p>