V LocalScript (ReplicatedFirst)
game:GetService("ScriptContext").Error:connect(function (Message,Stack,Source)
print(Source)
Event:FireServer(Message,Stack,Source)
end)
Output>LocalScript
V ServerScript(ServerScriptService)
game.ReplicatedStorage.ErrorSender.OnServerEvent:connect(function(Player,Message,Stack,Source)
print(Source)
end)
Output> nil

3 comments
Is the script located some where that the client can't access? For instance, ServerStorage or ServerScriptService? That would be the only thing I could think of.
Players.Vezious.PlayerGui.Main.Doors:2: attempt to concatenate a nil value
No one?