Fix issue in Lua debugger
Fix issue in Lua debugger

When a file could not be found on the system (for instance with compiled
lua file), the debugger was triggering a segmentation fault.

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