title: error in getting value from input that have ngIf directive
body: <p>I get an exception <code>Error TypeError and Error Context</code> when the submit button is clicked. If I will delete the <code>ngIf</code> directive It will work as excepted, The Full StackTrace:</p>
  
  <pre><code>PlayerNameFormComponent.html:8 ERROR TypeError: Cannot read property 'value' of undefined
  at Object.eval [as handleEvent] (PlayerNameFormComponent.html:8)
  at handleEvent (core.js:13547)
  at callWithDebugContext (core.js:15056)
  at Object.debugHandleEvent [as handleEvent] (core.js:14643)
  at dispatchEvent (core.js:9962)
  at eval (core.js:12301)
  at SafeSubscriber.schedulerFn [as _next] (core.js:4343)
  at SafeSubscriber.__tryOrUnsub (Subscriber.js:240)
  at SafeSubscriber.next (Subscriber.js:187)
  at Subscriber._next (Subscriber.js:128)
  </code></pre>
  
  <p><strong>PlayerNameFormComponent.html</strong></p>
  
  <pre><code>&lt;form (ngSubmit)="onSubmit(firstPlayer.value, secondPlayer.value)"&gt; // The line that throws the exception
  
    &lt;div class="input-field col s6"&gt;
      &lt;label for="firstPlayer"&gt;First Player Name&lt;/label&gt;
      &lt;input #firstPlayer id="firstPlayer" name="firstPlayer" type="text" class="validate"&gt;
    &lt;/div&gt;
  
    &lt;div *ngIf="isMultiplePlayers" class="input-field col s6"&gt;
      &lt;label for="secondPlayer"&gt;Second Player Name&lt;/label&gt;
      &lt;input #secondPlayer id="secondPlayer" name="secondPlayer" type="text" class="validate"&gt;
    &lt;/div&gt;
  
    &lt;button type="submit" class="waves-effect waves-light btn"&gt;Start&lt;/button&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p></p>
  
  <p><strong>PlayerNameFormComponent.ts</strong></p>
  
  <pre><code>export class PlayerNameFormComponent {
    isMultiplePlayers = true;
  
   public onSubmit(firstPlayer: string, secondPlayer: string) {
     console.log(firstPlayer);
     console.log(secondPlayer);
   }
  
  }
  </code></pre>
  
  <p><strong>EDIT:</strong>
  I changed my form tag to - <code>&lt;form (ngSubmit)="onSubmit(firstPlayer?.value, secondPlayer?.value)"&gt;</code> and now its print to console the firstPlayer input value and instead of secondPlayer value its prints <code>null</code></p>
  
  <p>Thanks for any kind of help :)</p>