/**
 * Filters out null elements from an array.
 * @param list List of elements that might be null.
 * @returns List of elements with nulls removed.
 */
export function pruneNull<T>(list: (T | null)[]): T[] {
  return list.filter((i) => i !== null) as T[];
}

export class NullDocumentError extends Error {}

/**
 * Throws if there is a null element in the array.
 * @param list List of elements that might have a null element.
 * @returns Same list of elements with a refined type.
 */
export function nullThrows<T>(doc: T | null, message?: string): T {
  if (doc === null) {
    throw new NullDocumentError(message ?? "Unexpected null document.");
  }
  return doc;
}

/**
 * Filters out null elements from an array.
 * @param list List of elements that might be null.
 * @returns List of elements with nulls removed.
 */
export function pruneNull<T>(list: (T | null)[]): T[] {
  return list.filter((i) => i !== null) as T[];
}

export class NullDocumentError extends Error {}

/**
 * Throws if there is a null element in the array.
 * @param list List of elements that might have a null element.
 * @returns Same list of elements with a refined type.
 */
export function nullThrows<T>(doc: T | null, message?: string): T {
  if (doc === null) {
    throw new NullDocumentError(message ?? "Unexpected null document.");
  }
  return doc;
}