React 16 ErrorBoundary messages in tests

```The above error occurred in the <ThemedContainer> component:
    in ThemedContainer
    in ProviderMock

Consider adding an error boundary to your tree to customize error handling behavior.
Visit https://fb.me/react-error-boundaries to learn more about error boundaries.

```

There is also an issue at the react repository. https://github.com/facebook/react/issues/11098