Tolk: Constant folding of out-of-range shift emits `PUSHNAN` instead of preserving runtime exception

[Gusarich]

The compiler folds 1 << 1024 into PUSHNAN at compile time, but the equivalent runtime operation throws range_chk (exit code 5). This changes observable behavior based on whether the shift amount is a constant.

const SHIFT: int = 1024;
const CONST_SHIFTED: int = 1 << SHIFT;

@noinline
fun runtime_shift(x: int, s: int): int { return x << s; }

fun onInternalMessage(s: int) {
    return (CONST_SHIFTED, runtime_shift(1, s));
}

Compiles to:

runtime_shift() PROC:<{  //  x s
  LSHIFT
}>

onInternalMessage() PROC:<{  //  s
  PUSHNAN               // const path: silently returns NaN
  1 PUSHINT
  ROT
  runtime_shift() CALLDICT  // runtime path: throws range_chk for s=1024
}>

TVM's LSHIFT throws range_chk (exit code 5) for shift counts outside 0–1023. The constant-folded version bypasses this check entirely and returns NaN instead.

For s = 1024, the runtime path throws while the const path silently yields NaN. The compiler should reject out-of-range constant shifts at compile time.