I get a compilation error in my app configured with create-react-app when trying to compile after importing a package that uses static class variables:

File was processed with these loaders:
 * ./node_modules/babel-loader/lib/index.js
You may need an additional loader to handle the result of these loaders.
| 
| class CrystVis {
>   static LEFT_CLICK = 1;
|   static MIDDLE_CLICK = 2;
|   static RIGHT_CLICK = 4;

What's a good way to have the babel loader handle these properly? Is it just a matter of configuration or do I need some specific plugin?