Resolve issue where error is not being returned to the caller.

[msvinaykumar]

Description

Execution errors in PromQL queries or query exceptions are being suppressed without passing error details back to the caller.

Fixes # (issue) Add thows and throw so errors are not suppressed and error details passed backed to caller.

Type of change

• [x] Bug fix
• [ ] New feature
• [ ] Docs update
• [ ] Breaking change (What changes might users need to make in their application due to this PR?)
• [ ] Requires DB changes

How has this been tested?

Please describe the tests that were run to verify your changes and steps to reproduce. Please specify any test configuration required.

• [ ] New Test X
• [x] Functional testsuite

Test Configuration

• Kubernetes clusters tested on:

Checklist :dart:

• [ ] Followed coding guidelines
• [ ] Comments added
• [ ] Dependent changes merged
• [ ] Documentation updated
• [ ] Tests added or updated

Additional information

Include any additional information such as links, test results, screenshots here