incr.comp.: Make sanity check in try_mark_green() aware of error conditions.
incr.comp.: Make sanity check in try_mark_green() aware of error conditions.

GBGamer/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,GBGamer/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust