Flutter web app will deploy to localhost but won't deploy to firebase

I've a flutter web app that'll run on the localhost perfectly but when I deploy it to firebase I get a blank page. In setting up firebase hosting I selected build/web as my public directory. I ran flutter build web which compiles the app. The build directory is created. My firebase.json file looks fine.(pos-ap/build/web for the public directory is correct)

{
  "hosting": {
    "public": "pos-app/build/web",
    "ignore": [
      "firebase.json",
      "**/.*",
      "**/node_modules/**"
    ],
    "rewrites": [
      {
        "source": "**",
        "destination": "/index.html"
      }
    ]
  }
}

Here is my index.html file

<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <meta content="IE=Edge" http-equiv="X-UA-Compatible">
  <meta name="description" content="A new Flutter project.">

  <!-- iOS meta tags & icons -->
  <meta name="apple-mobile-web-app-capable" content="yes">
  <meta name="apple-mobile-web-app-status-bar-style" content="black">
  <meta name="apple-mobile-web-app-title" content="pos">
  <link rel="apple-touch-icon" href="icons/Icon-192.png">

  <!-- Favicon -->
  <link rel="shortcut icon" type="image/png" href="favicon.png"/>

  <title>pos</title>
  <link rel="manifest" href="manifest.json">
</head>
<body>
  <!-- This script installs service_worker.js to provide PWA functionality to
       application. For more information, see:
       https://developers.google.com/web/fundamentals/primers/service-workers -->
  <script>
    if ('serviceWorker' in navigator) {
      window.addEventListener('load', function () {
        navigator.serviceWorker.register('flutter_service_worker.js');
      });
    }
  </script>
  <script src="https://www.gstatic.com/firebasejs/7.5.0/firebase-app.js"></script>
  <script src="https://www.gstatic.com/firebasejs/7.5.0/firebase-firestore.js"></script>
  <script src="https://www.gstatic.com/firebasejs/7.5.0/firebase-auth.js"></script>
  <script src="https://www.gstatic.com/firebasejs/7.5.0/firebase-analytics.js"></script>

  <script>
    // Your web app's Firebase configuration
    var firebaseConfig = {
    apiKey: "xxxxxxxxxxxxxxxxx",
    authDomain: "xxxxxxxxx",
    databaseURL: "xxxxxxxxx",
    projectId: "xxxxxx",
    storageBucket: "sxxxxxxxxxx",
    messagingSenderId: "xxxxxxx",
    appId: "1:xxxxxxxxx:web:xxxxxxxxxxxx7bc",
    measurementId: "G-xxxxxxxxx"
  };
    // Initialize Firebase
   // firebase.initializeApp(firebaseConfig);
    firebase.analytics();
  </script>


  <script src="main.dart.js" type="application/javascript"></script>
</body>
</html>

I'm not really familiar with web stuff. And apologies I can't really offer any more info. I suppose the only clue is that it works on localhost but not when deployed.

My root directory is..

|-pos-app
|-consumer-app
|-firebase.json

I'm trying to deploy pos-app which is a flutter app.