Fixed crash when checking stdin with config
Fixed crash when checking stdin with config

adan830/luacheck,tst2005/luacheck,adan830/luacheck,tst2005/luacheck,mpeterv/luacheck,linuxmaniac/luacheck,kidaa/luacheck,linuxmaniac/luacheck,xpol/luacheck,mpeterv/luacheck,kidaa/luacheck,mpeterv/luacheck,xpol/luacheck,xpol/luacheck