Use Never Types for Exhaustiveness Checking

Overview

Use never to ensure all cases in a union are handled.

When you add a new variant to a union type, TypeScript can automatically flag every switch statement that needs updating. This catches errors of omission at compile time.

When to Use This Skill

• Handling all cases of a tagged union
• Adding new variants to discriminated unions
• Writing switch statements that must be complete
• Want compile-time errors when cases are missed

The Iron Rule