Incorrect evaluation when multiplying the result of parenthesis

[brooksmckinley]

example:
eval("2 * 4 + 4") will correctly evaluate to 12 while eval("2 * (2 + 2) + (1 + 3)") or even eval(2 * (4) + (4)) will evaluate to 16, even though the two expressions should have the same result.

fn main() {
    assert_eq!(eval("2 * 4 + 4"), Ok(to_value(12)));
    assert_eq!(eval("2 * (4) + (4)"), Ok(to_value(12)));
}

thread 'main' panicked at 'assertion failed: `(left == right)`
  left: `Ok(Number(16))`,
 right: `Ok(Number(12))`', src/main.rs:7:5

[fengcen]

Sorry, I have only recently had time to fix this bug.
Thanks for your feedback.