looks like the beta 907 crash was due to $asctime(N) using N which is either too large positive or too large negative. I had used a loop where I had assumed an echo error would break out of the loop when $asctime(N) returned $null for being out of range. But instead it crashed when N went too far below range.
For negatives, as it continues further away from zero, it continues displaying time string Jan 01 1601 00:00:00 for a large range of negatives below the N belonging to that time string. However, it crashed when the N became too far below zero. The next line displayed for me, but changing -29228 to 29229 generated a crash.
//var -s %a $calc(-11644452000+365.2425*86400* -29228) | echo -a $asctime( %a )
For large positives, the new API supports years up through 9999, but crashes for any timestring displaying later than Dec 31 9999 23:59:59, so crashing the next command would require changing "*0" to another integer which would depend on the timezone.
//var -s %a $calc(253402300800+3600*0 ) | echo -a $asctime( %a )