Fail fast when LitAPI.setup has error

[aniketmaurya]

Before submitting

• Was this discussed/agreed via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure to update the docs?
• Did you write any new necessary tests?

What does this PR do?

Fixes #347

LitServe doesn't crash when there is an error in the LitAPI.setup method. This PR makes LitServe fail when setup has error.

PR review

Anyone in the community is free to review the PR once the tests have passed.
If we didn't discuss your PR in GitHub issues there's a high chance it will not be merged.

Did you have fun?

Make sure you had fun coding 🙃

[codecov]

Codecov Report

Attention: Patch coverage is 96.15385% with 1 line in your changes missing coverage. Please review.

Project coverage is 96%. Comparing base (23ba5e2) to head (2c54cb7).
Report is 2 commits behind head on main.

Additional details and impacted files

@@         Coverage Diff         @@
##           main   #356   +/-   ##
===================================
- Coverage    96%    96%   -0%     
===================================
  Files        22     22           
  Lines      1394   1408   +14     
===================================
+ Hits       1332   1345   +13     
- Misses       62     63    +1