Fixes runtime error when `ros env` is called without argument(s)
Fixes runtime error when `ros env` is called without argument(s)

hairyhenderson/rancheros,maxfierke/rancher-os,gizmotronic/os,rowhit/os,gpndata/os,imikushin/os,duguhaotian/os,duguhaotian/os,rancher/os,maxfierke/rancher-os,rancherio/os,luxas/os,rancherio/os,rancherio/os,luxas/os,1yvT0s/os,juliengk/os,1yvT0s/os,gizmotronic/os,hairyhenderson/rancheros,SvenDowideit/os,datawolf/os,maxfierke/rancher-os,1yvT0s/os,hairyhenderson/rancheros,imikushin/os,fentas/os,fentas/os,datawolf/os,rancher/os,fentas/os,rowhit/os,luxas/os,duguhaotian/os,ibuildthecloud/os,gpndata/os,ibuildthecloud/os,datawolf/os,gpndata/os,rowhit/os,juliengk/os,SvenDowideit/os