Error: <<=>>: bad evaluation: Cannot read property 'charAt' of undefined

I have one slave, born from a regular slave and an unknown father and raised in a tank, who has an error message instead of a description.

Error: <<=>>: bad evaluation: Cannot read property 'charAt' of undefined

I thought maybe a backwards compatibility update would fix it, but it did not. Everything seems fine on the full inspection screen, but she gets this instead of a summary. I've seen it in the penthouse and the schoolroom, so it doesn't seem location-dependent, and it's not repaired by moving her to a new assignment. All my other tank-born slaves are fine.