Test Coverage for `Counter.sol`

[pegahcarter]

This is a good first issue for anyone wanting to contribute to Frax Protocol.

Inspired by @tom2o17 in #13 (review), we need full test coverage on Counter.

Please comment on this issue if you want to own this task and submit a PR once ready for us to review. Once approved, we will merge your improvements into main.

Code coverage can be completed within a single test file of the aforementioned directory, with cleanup/removal of the other files.

[HemaDeviU]

please assign it to me

[HemaDeviU]

Hi, the files run successfully with 100% coverage. Please let me know if there is any specific task I should focus on.