Not sure why but I can see these messages in the beta bundles:

```
ReactDOM.render(): Invalid component element. Instead of passing a string like 'div', pass React.createElement('div') or <div />.
Missing injection for fiber findDOMNode
Missing injection for stack findDOMNode
Element appears to be neither ReactComponent nor DOMNode. Keys: %s
Target container is not a DOM element.
```

I'd like to understand why.
fs.writeFileSync(
      errorMapFilePath,
      JSON.stringify(invertObject(existingErrorMap), null, 2) + '\n',
      'utf-8'
    );
  }
  return function extractErrors(filepath) {
    const source = fs.readFileSync(filepath, 'utf-8');
    transform(source);
    flush();
  };
};