Remove table index by key in Lua

Question

I have this code

if not _elementdata[to] then
    _elementdata[to] = {}
end
if not _elementdata[to][key] then
    _elementdata[to][key] = {}
end
_elementdata[to][key] = { value = value, sync = sync or false }

But I have a issue when deleting it from the table.. I use

if _elementdata[source] then
    _elementdata[source] = nil
end

The first time I enter the game I have no errors, second time that I enter I get this error:

table index is nil

And if I keep reconnecting the errors increases with the number of reconnects.. so I guess that it's not deleting it at all.. btw here is the code to get the data and sent it to the clients:

for to, _ in pairs(_elementdata) do
    for key, _ in pairs(_elementdata[to]) do
        if to == root or _elementdata[to][key].sync then
            triggerClientEvent(source, "onClientElementSync", source, to, key, _elementdata[to][key].value)
        end
    end
end