I was debugging another issue when an assert triggered in EntityRep<>::setValue(). The direct cause of this assertion failure was function cpgrid::buildFaceToCell() calling setValue() with

other_cell = -1

There are a number of possibilities here

1. The assertion is wrong and it's okay to call the function with a negative index (unlikely)
2. The calling code in buildFaceToCell() needs a check for negative cell indices
3. The pinch processing code is wrong since it generates a negative cell index

At the top of my head I don't know which is which here so I'd like to discuss the matter. For the record, this issue presented when running the VOLVE_2020 model.