title: Angular 4 ERROR TypeError: Cannot read property 'filter' of undefined
body: <p>In a very large project web I still working on my company, some errors occurs while I testing the development version in the browser (Chrome and Firefox).
  Someone can help me?</p>
  
  <p>// update the message on screen</p>
  
  <pre><code>    this.parametrosMensagemService.setMessage(this.alert)
      this.pagerService.items = this.pagerService.items.filter(x =&gt; x.selecionado == "checked")
      this.setPage(1)
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/vt9rt.png" rel="nofollow noreferrer">Error log in Chrome Dev Tools</a></p>