SystemJS not loading modules from node_modules

I'm using SystemJS to load a simple JavaScript file:

define("main", ["require", "exports", "jquery"], function (require, exports, $) {
    "use strict";
    exports.__esModule = true;
    console.log($(document).html());
});

I'm loading it like so:

<script>require("systemjs")</script>
<script>
    SystemJS.import('./dist/app.js').then(null, console.error.bind(console));
</script>

But I am getting an error when I run it in electron:

GET file:///D:/Projects/myapp/app/jquery net::ERR_FILE_NOT_FOUND

Why is SystemJS not looking for jquery in node_modules like any other sane javascript loader? How do I get it to look there?