message: Documenting undefined behavior.
diff: @@ -315,6 +315,9 @@ impl ExecutionResult {
  ///
  /// The effects that are produced as part of this process would subract `max_payment_cost` from
  /// account's main purse, and add `max_payment_cost` to proposer account's balance.
  + ///
  + /// NOTE: This function assumes that `max_payment_cost <= account_main_purse_balance`.
  + /// Not obeying this restriction is a programming error with undefined behavior.
  pub fn new_payment_code_error(
  error: error::Error,
  max_payment_cost: Motes,
  