Zephir bug in incrementing array element

Hey.

Seems found a bug in incrementing an array element in Zephir. Possible same presents also for the decrement.

array a = [0, 0, 1, 1];

let a[0] += 1; // 1

let a[1] = a[1] + 1; // 1

let a[2] += 1; // 1 <- expected 2

let a[3] = a[3] + 1; // 2

print_r(a);

Zephir 0.12.12, PHP 7.2.24-0ubuntu0.18.04.1