fix (gb plugin): avoid panic when no argument is provided
fix (gb plugin): avoid panic when no argument is provided

constabulary/gb,inconshreveable/gb,tianon/gb,davidkaya/gb,tbruyelle/gb,mopemope/gb,constabulary/gb,davidkaya/gb,ches/gb,tianon/gb,hyper-carrot/gb,mopemope/gb,constabulary/gb,hyper-carrot/gb,mopemope/gb,lparkes/gb,ches/gb,tbruyelle/gb,inconshreveable/gb