Public class fields without a default value break the parser

[djfpaagman]

I was playing around with the LSP and noticed errors for some of my Stimulus controllers.

Debugging a bit I noticed that the parser fails on them, because we use some empty public class fields like so:

import { Controller } from "@hotwired/stimulus";

export default class extends Controller {
  someField;

  // this is just an example how we use them later, not related to the bug
  doSomething() {
    this.someField = "some value";
  }
}

• It does work if you set it with a value, like someField = "initial value".
• Having static in front of it also breaks

It fails on this line:

stimulus-parser/src/parser.ts

Line 45 in 31842f4

if (node.value.type === "ArrowFunctionExpression") {

with TypeError: Cannot read properties of null (reading 'type')

I guess those nodes don't have a type, so some other parsing exception should be added.

Happy to help, but I don't have a good idea in what direction to go.

edit later that day: I made a PR that implements a possible fix in #21!

[marcoroth]

Resolved via #21, thanks!