Webpack not transpiling JSX for custom addons

[travikk]

Describe the bug
In my project, I'm trying to add a custom storybook addon to provide extra capabilities for my stories.
I'm using CRA 2 + Storybook.

When I create a simple addon registrar, the app fails to start with the following error.

register.jsx:

addons.register('Controls', api => {
    addons.addPanel('Controls/panel', {
        title: 'UI Test',
        render: props => <span>Hi</span>
    });
});

Error I get in Chrome console:

Uncaught Error: Module parse failed: Unexpected token (28:25)
You may need an appropriate loader to handle this file type.
|     addons.addPanel('Controls/panel', {
|         title: 'UI Test',
>         render: props => <span>Hi</span>
|     });
| });
    at Object../src/__stories__/addons/controls/register.jsx (main.2aaaee8f95f5a00a5172.bundle.js:28)
    at __webpack_require__ (runtime~main.7b4918090cfe19b7778a.bundle.js:79)
    at Module../.storybook/addons.js (main.2aaaee8f95f5a00a5172.bundle.js:14)
    at __webpack_require__ (runtime~main.7b4918090cfe19b7778a.bundle.js:79)
    at Object.0 (main.2aaaee8f95f5a00a5172.bundle.js:39)
    at __webpack_require__ (runtime~main.7b4918090cfe19b7778a.bundle.js:79)
    at checkDeferredModules (runtime~main.7b4918090cfe19b7778a.bundle.js:46)
    at Array.webpackJsonpCallback [as push] (runtime~main.7b4918090cfe19b7778a.bundle.js:33)
    at main.2aaaee8f95f5a00a5172.bundle.js:1

Additionally, I'm extending the storybook webpack config to allow TS. Nothing fancy.

Any idea why is this not getting transpiled by default?

[slipo]

Perhaps it's related to #4995

I downgraded to 4.0.12 and everything works for me now. Before that I couldn't use any sort of custom addon. Seems like an urgent issue. Took me a while to figure out it wasn't a mistake on my part.

[stale]

Hi everyone! Seems like there hasn't been much going on in this issue lately. If there are still questions, comments, or bugs, please feel free to continue the discussion. Unfortunately, we don't have time to get to every issue. We are always open to contributions so please send us a pull request if you would like to help. Inactive issues will be closed after 30 days. Thanks!

[stale]

Hey there, it's me again! I am going close this issue to help our maintainers focus on the current development roadmap instead. If the issue mentioned is still a concern, please open a new ticket and mention this old one. Cheers and thanks for using Storybook!