fix: type error in mapSliceZone

[angeloashmore]

Types of changes

• Chore (a non-breaking change which is related to package maintenance)
• Bug fix (a non-breaking change which fixes an issue)
• New feature (a non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Description

This PR fixes a type error in mapSliceZone. The error was ignored via // @ts-expect-error in the source code, but the compiled output removed the comment. Thus, consumers that check the types of the installed package would throw a type error.

The typings have been fixed so // @ts-expect-error is no longer used.

Checklist:

• My change requires an update to the official documentation.
• All TSDoc comments are up-to-date and new ones have been added where necessary.
• All new and existing tests are passing.