Assertion helper function, to generate informative, type-safe assertions

assert.ts

export function assert(
  condition: unknown,
  message?: string
): asserts condition {
  if (!condition) {
    throw new AssertionViolationError(message);
  }
}

export class AssertionViolationError extends Error {
  override name = "AssertionViolation";

  constructor(message?: string) {
    super(message);
  }
}