Expose errors from the API endpoint in the UI

[ewanharris]

• 704acab - While working on this change I realised that the highlighted text would not change on a re-render and it appeared to be down to passing HTML elements, so this commit refactors the Highlight component to a functional component and to also take the contents as a string rather than a children of HTML elements.
• 462808c - Adds an error handler to the api-server that will massage the errors returned from express-oauth2-jwt-bearer into a JSON response for the UI. This is then handled in the frontend to try and pull the JSON (it's possible this could also be a raw HTML response) and then display it in an codeblock similar to the response

We could potentially extend this to also include examples of how to fix these issues.

For example:

The audience is different between the frontend and backend

A developer extends this sample to include requiredScopes but does not update the frontend/update their token

[frederikprijck]

I'm wondering if this isnt a bit too much for anyone using the sample to try and understand how to use our SDK. I know this isnt necessary related to our SDK, but not everyone might understand that.

In what event do we get back non-json?

[ewanharris]

Yeah I realise now this is probably too much for the sample, the only case that raw HTML would be returned is when the server errors with something other than a token error. So maybe in that instance we can just ignore?

[frederikprijck]

I would argue we could abstract this in a component? That way it's all at least seperated from basic integration?