assertPolicy = (
  allegedPolicy,
  message = 'Invalid LavaMoat policy; does not match expected schema'
) => {
  if (!isPolicy(allegedPolicy)) {
    throw new InvalidPolicyError(message)
  }
}
Assertion for a {@link LavaMoatPolicy}

@param {unknown} allegedPolicy
@param {string} [message] Assertion failure message
@returns {asserts allegedPolicy is LavaMoatPolicy}