Function assertNever

shared/src/utility.ts:13–21

(x: never, msg?: string)

// https://basarat.gitbook.io/typescript/type-system/discriminated-unions#throw-in-exhaustive-checks
export function assertNever(x: never, msg?: string): never {
	if (msg != null) {
		throw new Error(msg)
	}
	throw new Error(
		`Expected 'never', but got an unexpected value:
${JSON.stringify(x)}`,
	)
}

export function undefinedMap<T, R>(
	t: T | undefined,