Eliminate use of unwrap() in tests and codebase

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Currently, the project uses unwrap() extensively, including within test code. While unwrap() is often used in tests for simplicity, it's not ideal as it causes panics when the value is None or Err.

We would like to eliminate the use of unwrap() and replace it with expect() in the test code to provide more helpful error messages in case of failure. Additionally, unwrap() should be removed from the core codebase to avoid unnecessary panics, improving the robustness of the application.

The goal is to:

• In tests: Replace unwrap() with expect() to ensure clear error messages in case of failure.
• In the codebase: Avoid using unwrap() and handle errors more gracefully, using proper error handling strategies where appropriate.