2018-07-28 09:32:22: ERROR[Main]: ServerError: AsyncErr: ServerThread::run Lua: Runtime error from mod 'rmod' in callback LuaABM::trigger(): /home/xerox123/minetest/bin/../mods/rmod/grate.lua:42: attempt to index local 'def1' (a nil value) 2018-07-28 09:32:22: ERROR[Main]: stack traceback:          2018-07-28 09:32:22: ERROR[Main]:       /home/xerox123/minetest/bin/../mods/rmod/grate.lua:42: in function 'attempt_flow_to'                                                        2018-07-28 09:32:22: ERROR[Main]:       /home/xerox123/minetest/bin/../mods/rmod/grate.lua:84: in function 'grate_step' 2018-07-28 09:32:22: ERROR[Main]:       /home/xerox123/minetest/bin/../mods/rmod/grate.lua:106: in function 'flow'      2018-07-28 09:32:22: ERROR[Main]:       /home/xerox123/minetest/bin/../mods/rmod/grate.lua:116: in function </home/xerox123/minetest/bin/../mods/rmod/grate.lua:116>