- Replaced `values.get(0)` with `values.first()` for improved clarity and consistency across multiple files.
- Simplified conditional checks with `.is_empty()` and `format_args!` to enhance readability.
- Implemented `Default` trait for `VariableMode` directly within the enum.
- Updated error handling by boxing errors in `RepositoryError` and `CatalogError`.
- Replaced redundant `else` blocks with streamlined logic.
- Adjusted indentation and line breaks for structs, functions, and method calls to comply with Rust formatting standards.
- Improved error message formatting and consistency across `PkgTreeError` instances.
- Restructured long function arguments and chained calls for clarity and maintainability.
- Simplified conditional statements and loops for better readability.
- No functional changes introduced.
