Turbolink is loading before getting the session token from the Shopify App Bridge

[Lokesh_Saini]

I am implementing session token in our existing shopify app, It is a multi page application so I am using turbolink (suggested by shopify docs). 

See the below code that I'm using for generating Session Token.

<script src="https://unpkg.com/@shopify/app-bridge@2"></script>
<script src="https://unpkg.com/@shopify/app-bridge-utils"></script>

<script type="module">
  var host = "<?= \Session::get('host') ?>";

  const SESSION_TOKEN_REFRESH_INTERVAL = 2000;

  function retrieveToken(app) {

    window['app-bridge-utils'].getSessionToken(app).then(token => {
      window.sessionToken = token;
    });
  }

  document.addEventListener("turbolinks:request-start", function(event) {

     retrieveToken(app);
    
    var xhr = event.data.xhr;
    xhr.setRequestHeader("Authorization", "Bearer " + window.sessionToken);
  });

  document.addEventListener("turbolinks:render", function() {
    $("form, a[data-method=delete]").on("ajax:beforeSend", function(event) {
      const xhr = event.detail[0];
      xhr.setRequestHeader("Authorization", "Bearer " + window.sessionToken);
    });
  });

  document.addEventListener("DOMContentLoaded", async () => {
    var data = document.getElementById("shopify-app-init").dataset;
    var AppBridge = window["app-bridge"];
    var createApp = AppBridge.default;
    window.app = createApp({
      apiKey: '<?= env('App_Client_Id'); ?>',
      host: host,
    });

    var actions = AppBridge.actions;
    var TitleBar = actions.TitleBar;
    TitleBar.create(app, {
      title: data.page,
    });

    // Wait for a session token before trying to load an authenticated page
    await retrieveToken(app);

    // Keep retrieving a session token periodically
    keepRetrievingToken(app);

    // Redirect to the requested page when DOM loads
    var isInitialRedirect = true;
    redirectThroughTurbolinks(isInitialRedirect);

    document.addEventListener("turbolinks:load", function(event) {
      redirectThroughTurbolinks();
    });

    // Helper functions
    function redirectThroughTurbolinks(isInitialRedirect = false) {
      var data = document.getElementById("shopify-app-init").dataset;
      var validLoadPath = data && data.loadPath;
      var shouldRedirect = false;

      switch (isInitialRedirect) {
        case true:
          shouldRedirect = validLoadPath;
          break;
        case false:
          shouldRedirect = validLoadPath && data.loadPath !== "<?= url("/shopify/dashboard") ?>"; // Replace with the app's home_path
          break;
      }

      if (shouldRedirect) Turbolinks.visit(data.loadPath);
    }
    function keepRetrievingToken(app) {
      setInterval(() => {
        retrieveToken(app);
      }, SESSION_TOKEN_REFRESH_INTERVAL);
    }
  });
</script>

Problem: The "turbolinks:request-start" event is running before "DOMContentLoaded" event, due to this behaviour, token is not added on the first request's header.

Does this is expected behaviour?