Consider as corrupt a null-area bbox
Consider as corrupt a null-area bbox

Fixes crash with empty page_states

koreader/koreader,mihailim/koreader,mwoz123/koreader,lgeek/koreader,frankyifei/koreader,ashhher3/koreader,Markismus/koreader,apletnev/koreader,NickSavage/koreader,pazos/koreader,noname007/koreader,Hzj-jie/koreader,chihyang/koreader,chrox/koreader,Frenzie/koreader,NiLuJe/koreader,robert00s/koreader,ashang/koreader,koreader/koreader,houqp/koreader,poire-z/koreader,poire-z/koreader,Frenzie/koreader,NiLuJe/koreader