title: GTM not working on iOS
body: <p>I'm developing native iOS app and using firebaseSDK to send data to GTM.
  GTM started to log error on console and I can not see data on Google Analytics. I'm facing with error message below;</p>
  
  <pre><code>GoogleTagManager error: Error executing tag 1: TypeError: endsWith is not a function
  </code></pre>
  
  <p>What could be reason of the error? In what circumstances GTM logs this error?</p>