improved server callback

utils/server.lua

@@ -699,6 +699,16 @@ function Public.query_online_players()
     raw_print(message)
 end
 
+local function command_handler(callback, ...)
+    if type(callback) == 'function' then
+        local success, err = pcall(callback,...)
+        return success, err
+    else
+        local success, err = pcall(loadstring(callback),...)
+        return success, err
+    end
+end
+
 --- The command 'cc' is only used by the server so it can communicate through the webpanel api to the instances that it starts.
 -- Doing this, enables achivements and the webpanel can communicate without any interruptions.
 commands.add_command(
@@ -707,14 +717,13 @@ commands.add_command(
     function(cmd)
         local player = game.player
         if player then return end
-        local param = cmd.parameter
 
-        if param == nil then return end
-
-        local func, err = loadstring(param)
-        if not func then raw_print(err) return end
-        local _, err2 = pcall(func)
-        if err2 then raw_print(err2) return end
+        local callback = cmd.parameter
+        if not callback then return end
+        if not string.find(callback,'%s') and not string.find(callback,'return') then callback = 'return '..callback end
+        local success, err = command_handler(callback)
+        if not success and type(err) == 'string' then local _end = string.find(err,'stack traceback') if _end then err = string.sub(err,0,_end-2) end end
+        if err or err == false then raw_print(err) end
 end)
 
 --- The [JOIN] nad [LEAVE] messages Factorio sends to stdout aren't sent in all cases of