Using `react-refresh/babel` 0.4.0 is giving me this error on a large number of files:

```
ERROR in ../orbit-app/src/hooks/useStores.ts
Module build failed (from ../node_modules/babel-loader/lib/index.js):
TypeError: Cannot read property '0' of undefined
    at Function.get (/Users/nw/projects/motion/orbit/node_modules/@babel/traverse/lib/path/index.js:115:33)
    at NodePath.unshiftContainer (/Users/nw/projects/motion/orbit/node_modules/@babel/traverse/lib/path/modification.js:191:31)
    at PluginPass.exit (/Users/nw/projects/motion/orbit/node_modules/react-refresh/cjs/react-refresh-babel.development.js:546:28)
```

I narrowed down that file to the simplest thing that causes it:

```
import { useContext } from 'react'

export default () => useContext()
```

_Originally posted by @natew in https://github.com/facebook/react/issues/16604#issuecomment-528708174_
export function sum() {}
        export const Bad = 42;
    `),
    ).toMatchSnapshot();
  });
  it('registers top-level exported named arrow functions', () => {
    expect(
      transform(`
        export const Hello = () => {
          function handleClick() {}
          return <h1 onClick={handleClick}>Hi</h1>;
        };
        export let Bar = (props) => <Hello />;
        export default () => {
          // This one should be ignored.
          // You should name your components.
          return <Hello />;
        };
    `),
    ).toMatchSnapshot();
  });
  it('uses original function declaration if it get reassigned', () => {
    
    
    expect(
      transform(`
        function Hello() {
          return <h1>Hi</h1>;
        }
        Hello = connect(Hello);