Role edit page fails with JS error

[alexmt]

Describe the bug
Role edit page fails with JS error

To Reproduce
If we cannot reproduce, we cannot fix! Steps to reproduce the behavior:

1. Go to default project page and create any role
2. Click on role
3. See error:

Uncaught TypeError: Cannot read property 'map' of undefined
    at Object.children (project-role-policies-edit.tsx:37)
    at DataLoader../node_modules/argo-ui/src/app/shared/components/data-loader.tsx.DataLoader.render (data-loader.tsx:69)
    at finishClassComponent (react-dom.development.js:14537)
    at updateClassComponent (react-dom.development.js:14492)
    at beginWork (react-dom.development.js:15440)
    at performUnitOfWork (react-dom.development.js:19108)
    at workLoop (react-dom.development.js:19148)
    at HTMLUnknownElement.callCallback (react-dom.development.js:149)
    at Object.invokeGuardedCallbackDev (react-dom.development.js:199)
    at invokeGuardedCallback (react-dom.development.js:256)