Make more safe usage of _lastVertex.
Make more safe usage of _lastVertex.

colllin/openlayers,adh1365/openlayers,sanak/ol2,avinet/openlayers,kartverket/openlayers,pgiraud/openlayers,PetrDlouhy/openlayers,openlayers/ol2,colllin/openlayers,altamiracorp/openlayers,avinet/openlayers,openlayers/ol2,wet-boew/openlayers,ahocevar/ol2,sbrunner/openlayers,adh1365/openlayers,avinet/openlayers,Gnafu/openlayers,pvalsecc/openlayers,sanak/ol2,kartverket/openlayers,elbakai/openlayers,kartverket/openlayers,adh1365/openlayers,sanak/ol2,wet-boew/openlayers,georchestra/openlayers,openlayers/ol2,shevawen/openlayers,dracic/openlayers,altamiracorp/openlayers,owenmead/openlayers,altamiracorp/openlayers,pgiraud/openlayers,owenmead/openlayers,owenmead/openlayers,shevawen/openlayers,ahocevar/ol2,PublicStuff/openlayers,avinet/openlayers,pgiraud/openlayers,colllin/openlayers,sbrunner/openlayers,Gnafu/openlayers,PublicStuff/openlayers,kartverket/openlayers,PetrDlouhy/openlayers,PublicStuff/openlayers,georchestra/openlayers,sanak/ol2,pvalsecc/openlayers,PublicStuff/openlayers,v5analytics/openlayers,colllin/openlayers,ahocevar/ol2,pvalsecc/openlayers,dracic/openlayers,wet-boew/openlayers,v5analytics/openlayers,wet-boew/openlayers,altamiracorp/openlayers,Gnafu/openlayers,shevawen/openlayers,PetrDlouhy/openlayers,owenmead/openlayers,sbrunner/openlayers,elbakai/openlayers,georchestra/openlayers,elbakai/openlayers,elbakai/openlayers,Gnafu/openlayers,shevawen/openlayers,openlayers/ol2,v5analytics/openlayers,pvalsecc/openlayers,dracic/openlayers,pgiraud/openlayers,sbrunner/openlayers,dracic/openlayers,adh1365/openlayers,v5analytics/openlayers,PetrDlouhy/openlayers