Fix lint errors on new luals version (#384)

exp_gui/module/data.lua

@@ -87,7 +87,7 @@ function GuiData._metatable.__index(self, key)
 
     -- Check a given child table based on the object type
     assert(type(key) == "userdata", "Index type '" .. ExpUtil.get_class_name(key) .. "' given to GuiData. Must be of type userdata.")
-    local object_name = key.object_name
+    local object_name = key.object_name --- @diagnostic disable-line assign-type-mismatch
     if object_name == "LuaGuiElement" then
         local data = self._raw.element_data
         local player_elements = data and data[key.player_index]
@@ -110,7 +110,7 @@ end
 --- @param value unknown
 function GuiData._metatable.__newindex(self, key, value)
     assert(type(key) == "userdata", "Index type '" .. ExpUtil.get_class_name(key) .. "' given to GuiData. Must be of type userdata.")
-    local object_name = key.object_name
+    local object_name = key.object_name --- @diagnostic disable-line assign-type-mismatch
     if object_name == "LuaGuiElement" then
         local data = self.element_data
         local player_elements = data[key.player_index]

exp_gui/module/iter.lua

@@ -37,6 +37,7 @@ local function nop() return nil, nil end
 local function next_valid_element(elements, prev_index)
     local element_index, element = next(elements, prev_index)
     while element and not element.valid do
+        --- @cast element_index -nil
         elements[element_index] = nil
         element_index, element = next(elements, element_index)
     end
@@ -61,6 +62,7 @@ local function next_valid_player(scope_elements, players, prev_index, online)
         if index == nil then
             return nil, nil, nil
         end
+        --- @cast player -nil
 
         if online == nil or player.connected == online then
             local player_elements = scope_elements[player.index]