add error messages when incorrect env variables provided for ai-service

[mosabami]

Purpose

Previously an ok response is returned even if an incorrect openai key is provided. it also didnt provide useful error messages when incorrect environment variables are set. this PR fixes both problems

• ...

Does this introduce a breaking change?

[ ] Yes
[X ] No

Pull Request Type

What kind of change does this Pull Request introduce?

[X ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[ ] Other... Please describe:

How to Test

• Get the code

git clone [repo-address]
cd [repo-name]
git checkout [branch-name]
npm install

• Test the code

What to Check

Verify that the following are valid

• ...

Other Information

[pauldotyu]

LGTM