react-admin: Uncaught exception handling http error

We are working on a client for parse server, which displays some funny behavior around permissions. When an unauthenticated client attempts to list a class to which it doesn’t have access, the parse server returns 400 BAD REQUEST, with the content: {code: 119, error: "Permission denied for action find on class _User."}

This results in the following error on the client:

uncaught at handleFetch TypeError: Cannot read property 'map' of undefined
    at http://localhost:3000/static/js/bundle.js:45169:37
    at combination (http://localhost:3000/static/js/bundle.js:38863:30)
    at combination (http://localhost:3000/static/js/bundle.js:38863:30)
    at combination (http://localhost:3000/static/js/bundle.js:38863:30)
    at combination (http://localhost:3000/static/js/bundle.js:38863:30)
    at dispatch (http://localhost:3000/static/js/bundle.js:38323:23)
    at http://localhost:3000/static/js/bundle.js:44782:23
    at http://localhost:3000/static/js/bundle.js:43289:19
    at dispatch (http://localhost:3000/static/js/bundle.js:39018:19)
    at sagaDispatch (http://localhost:3000/static/js/bundle.js:42335:13)

We tried catching this in our HttpClient and disguising it as a 401, thus:

if (status === 400) {                                                 
    console.log('Got 400.  ugh.');                                    
    if (json && json.code === 119) {                                  
        console.log(json);                                            
        console.log('Trying to make it look like a 401');             
        return Promise.reject(new HttpError('401 UNAUTHORIZED', 401));
    }
}

but we still get the same error as above. What’s the correct way to indicate http errors?