feat(callback): implement callback validation

Prevent callbacks from being overwritten by other resources.
Throw an immediate error if the callback does not exist.

imports/callback/server.lua

@@ -4,9 +4,12 @@ local callbackTimeout = GetConvarInt('ox:callbackTimeout', 300000)
 
 RegisterNetEvent(cbEvent:format(cache.resource), function(key, ...)
     local cb = pendingCallbacks[key]
+
+    if not cb then return end
+
     pendingCallbacks[key] = nil
 
-    return cb and cb(...)
+    cb(...)
 end)
 
 ---@param _ any
@@ -24,12 +27,19 @@ local function triggerClientCallback(_, event, playerId, cb, ...)
         key = ('%s:%s:%s'):format(event, math.random(0, 100000), playerId)
     until not pendingCallbacks[key]
 
+    TriggerClientEvent('ox_lib:validateCallback', playerId, event, cache.resource, key)
     TriggerClientEvent(cbEvent:format(event), playerId, cache.resource, key, ...)
 
     ---@type promise | false
     local promise = not cb and promise.new()
 
     pendingCallbacks[key] = function(response, ...)
+        if response == 'cb_invalid' then
+            response = ("callback '%s' does not exist"):format(event)
+
+            return promise and promise:reject(response) or error(response)
+        end
+
         response = { response, ... }
 
         if promise then
@@ -96,7 +106,11 @@ local pcall = pcall
 ---Registers an event handler and callback function to respond to client requests.
 ---@diagnostic disable-next-line: duplicate-set-field
 function lib.callback.register(name, cb)
-    RegisterNetEvent(cbEvent:format(name), function(resource, key, ...)
+    event = cbEvent:format(name)
+
+    lib.setValidCallback(name, true)
+
+    RegisterNetEvent(event, function(resource, key, ...)
         TriggerClientEvent(cbEvent:format(resource), source, key, callbackResponse(pcall(cb, source, ...)))
     end)
 end