Error when parsing Mobx

[jhnns]

Environment

npm ls
├── @babel/[email protected]
├── @linaria/[email protected]
├── @linaria/[email protected]
├── @linaria/[email protected]
├── [email protected]
├── [email protected]
└── [email protected]

node -v
v16.13.1

On macOS Monterey

Description

When I tried to update to the latest Linaria version, I ran into a strange parsing bug. Originally it failed on dist/mobx.esm.js from the popular MobX library.

I've boiled down the code to the following example:

// main.js
import { css } from "@linaria/core";
import { b } from "./mobx.js";

css``;

// mobx.js
var _;

var a = void _;

function b(b) {
  void _;
}

export { a, b };

When trying to parse this, it will fail with:

ERROR in ./src/main.js
Module build failed (from ./node_modules/babel-loader/lib/index.js):
SyntaxError: /Users/jhnns/dev/jhnns/linaria-bug-repo/src/main.js: /Users/jhnns/dev/jhnns/linaria-bug-repo/src/mobx.js: Exporting local "b", which is not declared.
  7 | }
  8 |
> 9 | export { a, b };
    |             ^

Could be a Babel bug, but since it only happens in conjunction with Linaria I guess this is the right place to start 😁

Reproducible Demo

The example is pretty small and simple:

https://github.com/jhnns/linaria-bug-repo