The systemjs_issue2 from lddubeau

systemjs_issue2's Introduction

Versions

At the time of submitting the issue:

systemjs: 0.19.35 and 0.19.36 systemjs-builder: 0.15.25 and 0.15.26

Steps to reproduce the problem

Clone this repo: https://github.com/lddubeau/systemjs_issue2
npm install.
npm run build will produce js/out.js.
Open index.html in a server. (You cannot just load it from file:// due to cross-origin restrictions.)

You may need to reload, or play with the time parameter of setTimeout to get an error, the problem is a race condition.

The index.html contains the following:

<html>
  <head>
    <script type="text/javascript" src="node_modules/systemjs/dist/system.src.js"></script>
    <script type="text/javascript" src="system-config.js"></script>
    <script type="text/javascript">
      System.config({
      bundles: {
        "out.js": [ "lib/modB.js"],
      }
      });
      window.require = SystemJS.amdRequire;
      window.define = SystemJS.amdDefine;
      require(["modA"]);
      setTimeout(function () {
        require(["modC", "lib/modB"]);
      }, 10);
    </script>
  </head>
  <body>
  </body>
</html>

The system-config.js file contains:

System.config({
    baseURL: "js",
    packages: {
        '': {
            defaultExtension: "js"
        }
    }
});

Expected behavior

Everything should load without error. Files should be loaded once and only once.

Actual behavior

Two HTTP requests are made for modC.js

Errors on the console:

Uncaught (in promise) Error: (SystemJS) Cannot read property 'length' of null(…)
Uncaught (in promise) Error: (SystemJS) Cannot read property 'length' of null(…)

By putting breakpoints and stepping through code I've found that this error is triggered by normalizedDeps being null at this line.

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