Provide meaningful exception when using invalid element tag in lookup
Provide meaningful exception when using invalid element tag in lookup

jonfoster/pyxb2,CantemoInternal/pyxb,balanced/PyXB,jonfoster/pyxb-upstream-mirror,jonfoster/pyxb2,jonfoster/pyxb2,jonfoster/pyxb-upstream-mirror,jonfoster/pyxb1,jonfoster/pyxb1,CantemoInternal/pyxb,pabigot/pyxb,CantemoInternal/pyxb,balanced/PyXB,pabigot/pyxb,balanced/PyXB,jonfoster/pyxb-upstream-mirror