tree: fix rendering problems when resource.parent.parent does not yet exists
tree: fix rendering problems when resource.parent.parent does not yet exists

fingeronthebutton/RIDE,caio2k/RIDE,fingeronthebutton/RIDE,fingeronthebutton/RIDE,HelioGuilherme66/RIDE,caio2k/RIDE,HelioGuilherme66/RIDE,robotframework/RIDE,robotframework/RIDE,robotframework/RIDE,caio2k/RIDE,HelioGuilherme66/RIDE,HelioGuilherme66/RIDE,robotframework/RIDE