You will get one of these:
Uncaught (in promise) TypeError: Cannot read property 'toUpperCase' of undefined(…)
ReactCompositeComponent.js:870 Uncaught TypeError: Cannot read property 'displayName' of undefined
if you try to:
import { ComponentName } from 'ComponentName.jsx'
instead of:
import ComponentName from 'ComponentName.jsx'
This error:
Uncaught TypeError: Cannot read property 'toUpperCase' of undefined
might be caused by importing:
import { Link } from 'redux-router'
instead of
import { Link } from 'react-router'
Performance problems might be caused by 'redux-logger' and 'redux-devtools' packages.
Remove them from production build!
This error:
Uncaught TypeError: Cannot read property 'displayName' of undefined
at Array.forEach (native)
When you try to render an array of items with map callback:
{items.map(renderItem)}
You have to wrap the rendered result into <div></div>
tag.