Fixed problem if non-strings get into the index sort keys
Fixed problem if non-strings get into the index sort keys

valsdav/plastex,valsdav/plastex,dav94/plastex,valsdav/plastex,mungerd/plastex,dav94/plastex,dav94/plastex,valsdav/plastex,mungerd/plastex,mungerd/plastex,mungerd/plastex,dav94/plastex