Display error when `bin/grav install` hasn't been run instead of throwing exception
Display error when `bin/grav install` hasn't been run instead of throwing exception

sylvestrelucia/grav,sylvestrelucia/grav,userfrosting/learn,sylvestrelucia/grav,webuxr/iamrs,sylvestrelucia/grav,ccardinaux/grav-test,userfrosting/learn,Vivalldi/grav,toovy/grav,tomzx/blog.tomrochette.com,tomzx/blog.tomrochette.com,getgrav/grav,joeyhenricks/a-broke-vegan,joeyhenricks/a-broke-vegan,JamesPan/gravbox,stell/grav,userfrosting/learn,tomzx/blog.tomrochette.com,JamesPan/gravbox,dimayakovlev/grav,userfrosting/learn,getgrav/grav,toovy/grav,shortsofia/testesitegrav.github.io,Vivalldi/grav,gigago/grav,JamesPan/gravbox,notklaatu/grav,Sommerregen/grav,notklaatu/grav,JamesPan/gravbox,tomzx/blog.tomrochette.com,dimayakovlev/grav