Adjusted error handling and moved flag.Var to tree.flagSet.Var

[andreimerlescu]

No description provided.

[Copilot]

Pull Request Overview

This PR refactors flag handling and error management by introducing custom error types and routing flag registrations through a figTree instance rather than the global flag package.

• Replace fmt.Errorf calls with ErrInvalidValue, ErrConversion, and ErrInvalidType for richer error types
• Switch all flag.Var invocations in New… and WithAlias methods to tree.flagSet.Var
• Add Mutagenesis.Kind, consolidate and expose MutagenesisOf functions in a new mutagenesis.go

Reviewed Changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
parsing.go	Use ErrInvalidValue instead of fmt.Errorf in error returns
mutations_new.go	Update flag.Var → tree.flagSet.Var in all New* definitions
mutagenesis.go	New file: Mutagenesis.Kind(), global & tree MutagenesisOf
loading.go	Reorder imports
errors.go	Define ErrInvalidType, ErrConversion, ErrInvalidValue
conversions.go	Replace default fmt.Errorf with ErrConversion
assure.go	Replace fmt.Errorf in validators with ErrInvalidType
alias.go	Change global flag.Var → tree.flagSet.Var for aliases

Comments suppressed due to low confidence (1)

errors.go:34

• [nitpick] Using %T prints only the Go type of e.Got, not its value. Consider using %v to include the actual value or adjust the message for clarity, e.g., fmt.Sprintf("failed to convert %v (type %T) from %s to %s", e.Got, e.Got, e.From.Kind(), e.To.Kind()).

	return fmt.Sprintf("failed to convert %T type %s into %s", e.Got, e.From.Kind(), e.To.Kind())