获取 _flutter 在 flutter web 中未定义，仅在生产中定义

Question

获取 _flutter 在 flutter web 中未定义，仅在生产中定义

我在最近几次部署中出现了一个错误，但无法追踪它。仅当我部署到 firebase 网站时才会发生这种情况，调试工作没有任何问题。

Uncaught SyntaxError: Unexpected token '<' (at flutter.js:1:1)
(index):50 Uncaught ReferenceError: _flutter is not defined
    at (index):50:7

Run Code Online (Sandbox Code Playgroud)

这显示在浏览器控制台中。

这是我的index.html：

<!DOCTYPE html>
<html>

<head>
  <!--
    If you are serving your web app in a path other than the root, change the
    href value below to reflect the base path you are serving from.

    The path provided below has to start and end with a slash "/" in order for
    it to work correctly.

    For more details:
    * https://developer.mozilla.org/en-US/docs/Web/HTML/Element/base

    This is a placeholder for base href that will be replaced by the value of
    the `--base-href` argument provided to `flutter build`.
  -->
  <base href="$FLUTTER_BASE_HREF">

  <meta charset="UTF-8">
  <meta content="IE=Edge" http-equiv="X-UA-Compatible">
  <meta name="description" content="Trading made easy">
  <meta name="google-signin-client_id"
    content="xxx.apps.googleusercontent.com">

  <!-- 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="tornmarket">
  <link rel="apple-touch-icon" href="icons/Icon-192.png">

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

  <title>Torn Market</title>
  <link rel="manifest" href="manifest.json">
  <!-- <script>self.FIREBASE_APPCHECK_DEBUG_TOKEN = true;</script> -->
  <script>
    // The value below is injected by flutter build, do not touch.
    var serviceWorkerVersion = null;
  </script>
  <!-- This script adds the flutter initialization JS code -->
  <script src="flutter.js" defer></script>
</head>

<body>
  <script>
    window.addEventListener('load', function (ev) {
      // Download main.dart.js
      _flutter.loader.loadEntrypoint({
        serviceWorker: {
          serviceWorkerVersion: serviceWorkerVersion,
        }
      }).then(function (engineInitializer) {
        return engineInitializer.initializeEngine();
      }).then(function (appRunner) {
        return appRunner.runApp();
      });
    });
  </script>
</body>

</html>

Run Code Online (Sandbox Code Playgroud)