invalid key to 'next'

[Wolphwood]

Server :

local coords = {x = 0, y = 0, z = 0}
TriggerClientCallback(source, 'npwd:garage:getStreetName', coords)

Client :

RegisterClientCallback('npwd:garage:getStreetName', function(coords)
	return GetStreetNameFromHashKey(GetStreetNameAtCoord(coords.x,coords.y,coords.z))
end)

Result (server console)

[  script:npwd_garage] Error running system event handling function for resource npwd_garage: invalid key to 'next'
[  script:npwd_garage] stack traceback:
[  script:npwd_garage]  [C]: in function 'next'
[  script:npwd_garage]  citizen:/scripting/lua/scheduler.lua:187: in function <citizen:/scripting/lua/scheduler.lua:148>

The weirdest thing is, the callback return the expected value even with this error.. :|