A Decimal signalling NaN parameter crashes compilation with ValueError #303

A Decimal("sNaN") (signalling NaN) parameter crashes compilation with ValueError: cannot convert signaling NaN to float, wherever a parameter goes through jsonable (seen with RETURN range(2, 8, $s), s=Decimal("sNaN")). A quiet Decimal("NaN") and float NaN compile.

Found in the review of #302; the crash is older than that PR.

Expected: no crash at compile time. Either bind it as NaN like a quiet NaN, or refuse it with a clear Drivine error. Pick whichever matches how the NaN work (drivine4j #295/#409) settles NaN writes.

Python-only: the other libraries have no Decimal signalling NaN.