title: FormGroup ERROR TypeError: Cannot read property 'get' of undefined
body: <p>I am trying to get a value from my form and I am getting this error:
    <em>ERROR TypeError: Cannot read property 'get' of undefined</em></p>
  
  <pre><code> addMessage: FormGroup;
   get message(){ return this.addMessage.get('message').value}
  </code></pre>
  
  <p>Html:</p>
  
  <pre><code> &lt;form [formGroup]="addMessage" (ngSubmit)="sendMessage()"&gt;
        &lt;input formControlName="message" class="input" type="text"&gt;
        &lt;button type="submit" class="button is-primary"&gt;Send&lt;/button&gt;
    &lt;/form&gt;
  </code></pre>