bug: Slider does not work with autoupdate

[Vac1911]

Describe the bug Slider throws error in latest release after calling basalt.autoUpdate.

The error happens on line 138 of Slider https://github.com/Pyroxenium/Basalt/blob/8dd8e63d21752f2fe621b04b9db0aeb155fedf0d/Basalt/objects/Slider.lua#L138

To Reproduce

local basalt = require("basalt")
local main = basalt.createFrame()
local slider = main:addSlider():setBarType("horizontal")

basalt.autoUpdate()

Expected behavior

No error

Screenshots

I am running the latest version.