Add module checks for all components about substrate-front-end-template

[shawntabrizi]

An empty render should return null:
https://stackoverflow.com/questions/42083181/is-it-possible-to-return-empty-in-react-render-function

Returning anything like false wont work as it expects some component and you get the error I posted.

[JoshOrndorff]

Examples of how to do such a check https://github.com/substrate-developer-hub/substrate-ui-template/blob/8d01a81cf5c3f83def720259afd5468d0c35138e/src/App.jsx#L137-L141

[shawntabrizi]

An updated way to do this check is here:
37a0622

It keeps the check within the component itself, which is a pattern we should TOTALLY be following here.

Note the patch at the end of the conversation so that a failed check returns null

[JoshOrndorff]

Agree, this is a good idea. What's the motivation for returning null? It otherwise would have returned false I think.