Fix error in Lua
Fix error in Lua

On some real traffic, the connection was nil. The error should not be
reported.

lcheylus/haka,nabilbendafi/haka,lcheylus/haka,Wingless-Archangel/haka,LubyRuffy/haka,haka-security/haka,haka-security/haka,lcheylus/haka,nabilbendafi/haka,nabilbendafi/haka,haka-security/haka,LubyRuffy/haka,Wingless-Archangel/haka