The stone statue bunch in RPY level caused an internal error
"You change position with the stone statue. *** An internal error has occurred. Stacking monsters (a stone statue/281 {0, 16641} [46,10] with a stone golem/55 [46,11]) at (46, 11) is not allowed (L:11, 5; LI: 115). *** I'm trying to fix this by simply deleting the stone statue."
Game managed to continue. Precisely before this happened, the
"A stone golem grows out of the ground and takes its position as a silent guard."