feat(cache): send oldValue to onCache

Internally handle the cache events to prevent race conditions
and resolve #618.
Improved types.

init.lua

@@ -91,9 +91,6 @@ end
 local lib = setmetatable({
     name = ox_lib,
     context = context,
-    onCache = function(key, cb)
-        AddEventHandler(('ox_lib:cache:%s'):format(key), cb)
-    end
 }, {
     __index = call,
     __call = call,
@@ -173,14 +170,27 @@ end
 ---Caches the result of a function, optionally clearing it after timeout ms.
 function cache(key, func, timeout) end
 
+local cacheEvents = {}
+
 local cache = setmetatable({ game = GetGameName(), resource = resourceName }, {
-    __index = context == 'client' and function(self, key)
+    __index = function(self, key)
+        cacheEvents[key] = {}
+
         AddEventHandler(('ox_lib:cache:%s'):format(key), function(value)
+            local oldValue = self[key]
+            local events = cacheEvents[key]
+
+            for i = 1, #events do
+                Citizen.CreateThreadNow(function()
+                    events[i](value, oldValue)
+                end)
+            end
+
             self[key] = value
         end)
 
         return rawset(self, key, export.cache(nil, key) or false)[key]
-    end or nil,
+    end,
 
     __call = function(self, key, func, timeout)
         local value = rawget(self, key)
@@ -197,6 +207,14 @@ local cache = setmetatable({ game = GetGameName(), resource = resourceName }, {
     end,
 })
 
+function lib.onCache(key, cb)
+    if not cacheEvents[key] then
+        getmetatable(cache).__index(cache, key)
+    end
+
+    table.insert(cacheEvents[key], cb)
+end
+
 _ENV.cache = cache
 
 local notifyEvent = ('__ox_notify_%s'):format(cache.resource)