Add Null Overloader to handle null values

[fawazsuleiman]

Description

If left or right is null in the case that a value has not been provided yet, a RuntimeException is thrown. This overloader will handle cases where both left and right are null.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Code refactoring
• Performance improvement
• Test updates

Testing

• All existing tests pass (composer test)
• Added new tests for the changes
• Static analysis passes (composer test:types)
• Code coverage remains at 100%
• Mutation testing passes (composer test:infection)

Code Quality Checklist

• My code follows the project's coding standards
• I have run vendor/bin/pint to format my code
• I have added/updated PHPDoc comments where necessary
• I have updated the documentation (if applicable)
• My changes generate no new warnings or errors
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

Documentation

• I have updated the README.md (if applicable)
• I have updated the CHANGELOG.md
• I have added/updated code examples (if applicable)

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By submitting this pull request, I confirm that my contribution is made under the terms of the MIT license.