Got this bug notice in red, in latest version 3.87. Please see the pic / log.
It happened when attempting to make Clothes->Fur Hood, using a recently produced forest reindeer fur and a 6ft piece of linen thread. The item seems to have been made OK. And there was no hang/crash, only the ominous message in red.
The only thing weird about the reindeer fur used that I can think of, is that it possibly came from being a formerly "cured" one. It soaked and turned into a proper fur without issues. Repeating the task gives the exact same error in red.
PS: Forgot to mention that I'm experimenting with modding, changed the crafting skill on clothes from COMMON to TEXTILECRAFT and to HIDEWORKING on leather items in my game, in case that may be relevant to the bug's appearance somehow. Those changes make sense in my head, for making clothing deserves having an existing specialized skill linked to it, but not sure if this is causing something unexpected.