[error] Remove redundant Error wrappers + Add RuntimeError type + Replace DecimoError with specific error types

[forfudan]

This PR refactors Decimo’s error-handling to raise the library’s typed DecimoError[...] aliases directly (e.g., ValueError, OverflowError) instead of wrapping them in Error(...), introduces a RuntimeError type, and updates call sites/tests accordingly.

Changes:

• Remove redundant Error(...) wrappers across TOML parsing, numeric parsing, and arithmetic modules.
• Add RuntimeError as a DecimoError[...] alias and update runtime-infrastructure failure sites (e.g., MPFR availability/allocation).
• Replace uses of the generic DecimoError wrapper with more specific error types (and update tests to match).

[Copilot]

Pull request overview

This PR refactors Decimo’s error-handling to raise the library’s typed DecimoError[...] aliases directly (e.g., ValueError, OverflowError) instead of wrapping them in Error(...), introduces a RuntimeError type, and updates call sites/tests accordingly.

Changes:

• Remove redundant Error(...) wrappers across TOML parsing, numeric parsing, and arithmetic modules.
• Add RuntimeError as a DecimoError[...] alias and update runtime-infrastructure failure sites (e.g., MPFR availability/allocation).
• Replace uses of the generic DecimoError wrapper with more specific error types (and update tests to match).

Reviewed changes

Copilot reviewed 24 out of 24 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
src/decimo/toml/parser.mojo	Raises ValueError directly for TOML parse/path/key errors.
src/decimo/tests.mojo	Updates test helper to rethrow parse failures using ValueError alias.
src/decimo/str.mojo	Raises ValueError directly for numeric-string parsing validation errors.
src/decimo/errors.mojo	Adds RuntimeError alias; changes DecimoError generic param to StringLiteral.
src/decimo/decimal128/special.mojo	Raises typed errors directly for factorial bounds/overflow.
src/decimo/decimal128/rounding.mojo	Raises OverflowError directly for rounding overflow conditions.
src/decimo/decimal128/exponential.mojo	Replaces DecimoError wrappers; rethrows failures with typed errors.
src/decimo/decimal128/decimal128.mojo	Removes DecimoError wrapper usage; uses ConversionError/ValueError/OverflowError.
src/decimo/decimal128/constants.mojo	Raises ValueError directly for invalid constant lookup input.
src/decimo/decimal128/arithmetics.mojo	Raises typed errors directly for arithmetic failures; adjusts rethrowing.
src/decimo/biguint/biguint.mojo	Removes DecimoError wrappers; adjusts dunder error rethrows and imports.
src/decimo/biguint/arithmetics.mojo	Removes DecimoError wrappers; uses typed errors for arithmetic edge cases.
src/decimo/bigint10/bigint10.mojo	Removes DecimoError wrappers; uses ConversionError/ZeroDivisionError where relevant.
src/decimo/bigint10/arithmetics.mojo	Removes DecimoError wrappers; rethrows division/modulo failures with ZeroDivisionError.
src/decimo/bigint/number_theory.mojo	Replaces DecimoError with ValueError for invalid modular arithmetic inputs.
src/decimo/bigint/exponential.mojo	Replaces DecimoError with ValueError for invalid sqrt input.
src/decimo/bigint/bigint.mojo	Removes DecimoError wrappers; uses ZeroDivisionError for division-related dunders.
src/decimo/bigint/arithmetics.mojo	Removes DecimoError wrappers; uses ValueError/ZeroDivisionError for invalid operations.
src/decimo/bigfloat/bigfloat.mojo	Uses new RuntimeError for MPFR availability/allocation failures; keeps ConversionError for parsing/export.
src/decimo/bigdecimal/trigonometric.mojo	Raises ValueError directly for undefined trig reciprocals.
src/decimo/bigdecimal/exponential.mojo	Raises typed errors directly for invalid power/root/log inputs and overflow.
src/decimo/bigdecimal/constants.mojo	Raises ValueError directly for invalid precision.
src/decimo/bigdecimal/bigdecimal.mojo	Removes DecimoError wrappers; uses ConversionError/ValueError directly.
src/decimo/bigdecimal/arithmetics.mojo	Raises ZeroDivisionError directly for division/modulo by zero.

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