feat: removes formatter from Error function

[rjfonseca]

The default formatter was caused unwanted behavior with external wrapping methods, like fmt.Errorf, because of how the Error functions was implemented and the use of GetRootError.

Some context was lost in those cases.

The solution was to remove de formatter from the Error function. Now the Error function will only print the inner Error(). This will preserve the context of other errors.

The formatters are still available to be used directly or vai calling the new Format() function that will apply the formatter set in the error chain or the Default one. This was the previous behavior of the Error functions.

[Copilot]

Pull Request Overview

This PR refactors error formatting so that calling Error() returns only the inner error message, and introduces a new Format() function to apply the full formatter chain. Tests and examples have been updated to use Format() instead of relying on the default Error() formatting.

• Modify Error.Error() to return only the inner error.
• Add Format() helper and adjust existing formatters.
• Update tests and examples to call Format() and adjust expected outputs.

Reviewed Changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
with_test.go	Switch tests from err.Error() to Format(err) and updated expected strings.
value_test.go	Add new TestValueAllSlice and test empty/error value slicing.
root_error_test.go	Add test covering GetRootError with fmt.Errorf wrapping.
formatter_test.go	Update formatter tests to use GetFormatter(err)(err) and Format().
formatter.go	Introduce Format() function and update formatter implementations.
example/main.go	Update example calls to use Format() instead of printing err.
error_test.go	Add tests for nil inner error and mixed error chains.
error.go	Change Error() to bypass default formatter and return inner error.
README.md	Extend example showing both Error() and Format() usage.