title: Angular material stepper next step showing create instead of 1
body: <p>I am working on stepper, i want to disable next step until all filled should be filled so i made linear to true in 
  html file </p>
  
  <pre><code>&lt;mat-horizontal-stepper [linear]="true" #stepper&gt;
          &lt;mat-step [stepControl]="firstFormGroup"&gt;
            &lt;form [formGroup]="firstFormGroup"&gt;
  </code></pre>
  
  <p>it's working fine but whenever i am going to next step, "1" becomes "cre"
  on inspecting i got</p>
  
  <p><a href="https://i.stack.imgur.com/yMpiX.png" rel="noreferrer"><img src="https://i.stack.imgur.com/yMpiX.png" alt="enter image description here"></a></p>
  
  <p>i didn't user create anywhere in my code it's coming from mat-icon</p>