Init without args gives 'TypeError': Cannot read property 'node' of undefined

[fpapado]

The problem

I have an application where I call init with no arguments. If I leave it like that, then the hmr script throws.

If I add {} as the argument, it works.

// This throws
const app = Elm.Main.init();

// This works
const app = Elm.Main.init({});

The source

I traced that back to

elm-hot/resources/hmr.js

Line 172 in 3372608

var domNode = args['node'] ? wrapDomNode(args['node']) : document.body;

 if (originalInit) {
                module.init = function (args) {
                    var elm;
                    var portSubscribes = {};
                    var portSends = {};
                    var domNode = args['node'] ? wrapDomNode(args['node']) : document.body;

The code there assumes that args already exists, and then checks whether there's a node or not.

A solution

I thought to open an issue instead of sending a drive-by PR.
One solution could be just more ternaries, or splitting it out to something named and nicer to debug.

var domNode = !args ? document.body : args['node'] ? wrapDomNode(args['node']) : document.body;

But the root question I suppose is whether "init without arguments means document.body".
I looked through the docs, and that seems to be the case, at least for the current Browser programs.
It seems that package.elm-lang.org also uses init without args, and possibly more user code.

view-source:https://package.elm-lang.org/packages/elm/browser/latest/Browser#application