Missing configuration creates runtime error that's unfriendly for beginners

[matthewpereira]

Expected behavior

If a user charges ahead with running the sample application before configuring their Auth0 tenant or environment configuration, the sample application should detect the problem and point them in the right direction to rectify the situation.

Actual behavior

Proposal

Adding a try/catch that either triggers an error page component that we define elsewhere, or an error.message that we define inline on the app/page.tsx like this:

We can use this error to point users toward the README.md / bootstrapping script, or direct them to manually edit their .env file to ensure that the secret value (or perhaps other values that might be missing) are correct.

Feedback welcome on how we'd like to handle error cases so that it's scalable, and doesn't clutter up too many files.