/**
 * Removes null and undefined values from an array, narrowing to NonNullable<T>.
 */
export function filterNils<T>(arr: readonly (T | null | undefined)[]): NonNullable<T>[] {
	if (!Array.isArray(arr)) {
		throw new TypeError(`filterNils expects an array, got ${typeof arr}`);
	}
	return (arr as readonly (T | null | undefined)[])
		.filter((item): item is NonNullable<T> => item != null);
}