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_
}
          
          
          const node = path.node;
          if (seenForOutro.has(node)) {
            return;
          }
          seenForOutro.add(node);
          
          registrationsByProgramPath.delete(path);
          const declarators = [];
          path.pushContainer('body', t.variableDeclaration('var', declarators));
          registrations.forEach(({handle, persistentID}) => {
            path.pushContainer(
              'body',
              t.expressionStatement(
                t.callExpression(t.identifier('$RefreshReg$'), [
                  handle,
                  t.stringLiteral(persistentID),
                ]),
              ),
            );
            declarators.push(t.variableDeclarator(handle));
          });
        },
      },
    },
  };
}