exhaustiveness-checking

To enforce exhaustiveness checking in TypeScript switch statements, add an assertUnreachable function in the default branch. This surfaces missing union variants as compile-time type errors, preventing runtime omissions when handling discriminated unions.

The assertUnreachable pattern forces compile-time errors when a new variant is added to a discriminated union. By placing it in the default branch of a switch statement, it ensures every union case is explicitly handled, preventing runtime omissions.

To get a compile-time error when adding a new variant to a discriminated union, use an assertUnreachable default branch in your switch statements. This enforces exhaustiveness by surfacing missing cases as type errors during development.

You need exhaustiveness checking when handling tagged unions in TypeScript to prevent runtime omissions. It is applicable when adding new variants to discriminated unions and ensuring all cases are handled consistently in switch statements.

The best way to handle missing cases in TypeScript discriminated unions is using the assertUnreachable pattern in the default branch. This enforces exhaustiveness by triggering compile-time type errors for unhandled switch statement cases.