Improve test code coverage for src/plugin/manager.ts

[palisadoes]

Goal

The goal of this issue is to improve the code coverage for this file

Tasks

1. Review the file to identify sections of code that are being ignored by Codecov or are not covered by tests.
2. Create or update test cases to ensure 100% coverage for the file.
3. Remove any /* istanbul ignore */ or equivalent statements that bypass code coverage reporting, unless absolutely necessary.

Resources

1. Refer to the foundational documentation on writing test cases in the repository.
2. Check the Codecov report for details on the uncovered lines.

Acceptance Criteria

1. All sections of the file are covered by tests.
2. Code coverage for the file reaches 100%.
3. PR created with necessary updates, passing all checks and reviews.
4. All tests must be valid

If the file is not used in the code base:

1. Remove the file and its test cases
2. Submit a PR with the removed file(s) as the PR for this issue

Other

If you are new to testing, refer to past test code coverage improvement PRs

[rudra-sah00]

hey i would like work on this issue @palisadoes

[palisadoes]

Please read the ISSUE_GUIDELINES.md file on how to use the auto assign feature