Tree data vanishes after timeout

[ms609]

On two occasions, after leaving tree search to time out (60 mins elapsed) and then some (overnight), dataset seems to have vanished on returning. Command line gives

-- Find local optimum ------------------------------------------------------------------------------
>  TBR depth 5; keeping max 100 trees; k = Inf.
i 2021-11-09 15:27:09: Score to beat: 1425

-- Escape local optimum ----------------------------------------------------------------------------
> 6 ratchet iterations; TBR depth 1; max. 34 hits; k = Inf.
> 2021-11-09 15:53:41: Score to beat: 1422
> Ratchet iteration 1 @ 15:53:41; score to beat: 1422 
x Did not hit best score 1422
i Stopping search at 2021-11-09 16:59:02: 60 minutes have elapsed.  Best score was 1422.
Increase `maxTime` for longer runs.
√ 2021-11-09 16:59:02: Tree search terminated with score 1422
Warning: Error in [[: subscript out of bounds
  [No stack trace available]
Warning: Error in [[: subscript out of bounds
  [No stack trace available]

Possibly a Chrome issue (sending tab to sleep?); didn't happen a couple of minutes after a 60-min timeout. Can we reproduce with a very short timeout?