Character OOP Type Error Help

[P_rceptionNull (Noxira)]

Hello! I’m having issues with Type Errors in a module script I’m writing. I’m kind of new to strictly-typed lua, and I’m not sure if this is just something I should ignore or put more thought/effort into.

On line 53, when I call self:destroy(), I get a type error stating: Type 'RBXScriptConnection' could not be converted into 'nil' in an invariant context. I also get a type error on line 77, when I run this code: self.died_connection = nil. This error says: Type 'nil' could not be converted into 'nil&~(false?)'; this is because in the 1st component of the intersection, the negation `false`, and `nil` is not a subtype of `false?`

No matter what I do, I can’t get the type errors to go away. I’m not sure if I should just live with the red underlines or try to find the root cause.

--!strict

-------------- 
-- SERVICES -- 
-------------- 
local Players = game:GetService("Players")

--------------- 
-- CONSTANTS -- 
--------------- 

----------- 
-- TYPES -- 
----------- 
export type characterObj = {
	model: Model,
	humanoid: Humanoid,
	animator: Animator,
	player: Player?,
	died_connection: RBXScriptConnection
}

--------------- 
-- VARIABLES -- 
--------------- 

------------ 
-- MODULE -- 
------------ 
local CharacterService = {}
CharacterService.__index = CharacterService

----------------------- 
-- PRIVATE FUNCTIONS -- 
----------------------- 

--------------------- 
-- PRIVATE METHODS -- 
--------------------- 

---------------------- 
-- PUBLIC FUNCTIONS -- 
---------------------- 
function CharacterService.new(character: Model): characterObj
	local self = setmetatable({}, CharacterService)

	self.model = character
	self.humanoid = character:WaitForChild("Humanoid") :: Humanoid
	self.animator = self.humanoid:WaitForChild("Animator") :: Animator
	self.player = Players:GetPlayerFromCharacter(character) :: Player?

	self.died_connection = self.humanoid.Died:Connect(function()
		self:destroy()
	end)

	return self
end

function CharacterService.init(): ()
	-- placeholder
end

function CharacterService.start(): ()
	-- placeholder
end

-------------------- 
-- PUBLIC METHODS -- 
-------------------- 
function CharacterService:destroy()
	if self.model then
		self.model:Destroy()
	end

	if self.died_connection then
		self.died_connection:Disconnect()
		self.died_connection = nil
	end

	self.model = nil
	self.humanoid = nil
	self.animator = nil
	self.player = nil
end

--------------- 
-- EXECUTION -- 
--------------- 

------------- 
-- CLOSING -- 
------------- 
return CharacterService

Again, I’m new to using type annotations and OOP structures in Roblox. Thanks for your patience and responses
- P_rceptionNull (Noxira)

[Fayer_watery]

The issue might be that your characterObj type defines properties like died_connection as non-nil, but you’re trying to set them to nil in the destroy() function. Adding ? to the types (like RBXScriptConnection?) should fix the errors by allowing them to be nil.

[smashblox55 (Clinomi)]

Make sure to disconnect your connection in Destroy().

function CharacterService:Destroy()
    -- Add any other cleanups for objects
    -- For example, if you had a part you created in the constructor, do self.Part:Destroy()
    self.died_connection:Disconnect()

    table.clear(self) -- This just sets all values inside a table to nil (in this case clearing itself)
end

You got this error because it was trying to set self.died_connection to nil while it was still connected.
Just properly clean up any objects with their Destroy() method, and clear everything else.

[smashblox55 (Clinomi)]

Also, partially unrelated, but you should add your instance methods to the type:

export type CharacterService = {
    model: Model,
    humanoid: Humanoid,
    animator: Animator,
    player: Player?,
    died_connection: RBXScriptConnection,
    init: () -> (), -- First set of parentheses represents method parameters, second set represents what it returns.
    start: () -> (),
    destroy: () -> (),
}

[P_rceptionNull (Noxira)]

This worked, thank you. I’ll also look into your other post.