Just a few heads up:
This bug is still present in build 1308
The NaN biomass can occur as early as having taken 1 GaloMax (Cumflation→Ingest when having any fluid inside)
When one takes 2 Galomax, it can lead to the following crash at the next orgasm if Venting is enabled:
Version: 0.69.420 -BACKER#1308
ERROR: ballFullness is not a number.
This bug
is fixed by saving and reloading; however, this resets the biomass reserve back to 0.
In the included save file, to reproduce crash:
Codex→Appearance→Shift Goo→ToggleVent→Next→Cumflation→Ingest→Yes→Next→Back→Back→Back
Then just trigger an orgasm (via Masturbation)
This also demonstrates how rough the lack of context is in the Goo Shift Menu without access to the text.