title: Cannot set property 'textContent' of null error
body: <p>I am getting this error in SAP UI5 app.</p>
  
  <pre><code>updateFinished: function (count) {
      itemCount = count.getParameters().total;
      var labelId = thats2.getView().byId("page").getCustomHeader().getContentMiddle()[0].sId;
      document.getElementById(labelId).textContent = "Requests (" + itemCount + ")";
  }
  </code></pre>
  
  <p>what is wrong with the code. Do I need to do null check before assignment?
  Thanks</p>