Macro divmod_op 

macro_rules! divmod_op {
    ($fn_name:ident, $op_name:literal, $checked_fn:ident, $error_msg:literal) => { ... };
}

Macro to generate division/modulo operation functions (DIV, MOD).

Checks for division by zero AND the signed overflow case i64::MIN / -1 (which panics in Rust debug mode and wraps in release mode).