Attempt to index nil with "FindFirstChildOfClass"?

[Resurrected_Dove (rs_dv)]

Hey! so currently im working on a limited rendering viewport system. However for some reason I keep getting this "attempt to index nil with “FindFirstChildOfClass” error even though the part is clearly there.

local ViewportHandler = require(script.Parent.ViewportHandler)
local Frame = script.Parent.ViewportFrame
local RunService = game:GetService("RunService")
local VF_Handler = ViewportHandler.new(Frame)

local BoxCFrame = workspace.CameraViewportPart.CFrame * CFrame.new(Vector3.new(0, 0, -38.5))
local BoxSize = Vector3.new(75,75,75)
local Params = OverlapParams.new() -- Defaulted to blacklist,
Params.FilterDescendantsInstances = { workspace.CameraViewportPart }

local lastParts = {}

while true do
	BoxCFrame = workspace.CameraViewportPart.CFrame * CFrame.new(Vector3.new(0, 0, -38.5))
	local parts = workspace:GetPartBoundsInBox(BoxCFrame,BoxSize,Params)
	local partsAdded, partsRemoved = {}, {}
	for i, part in ipairs(parts) do
		if not table.find(lastParts, part) then
			table.insert(partsAdded, part) -- this part was added
			if not part.Parent:FindFirstChildOfClass("Humanoid") then
				if not part.Parent.Parent:FindFirstChildOfClass("Humanoid") then
					if not part:FindFirstChild("RenderObjectValue") then
						renderpart = VF_Handler:RenderObject(part,workspace.Commands.FPS.Value)
					end
				end
			end
			if part.Parent:FindFirstChildOfClass("Humanoid") then
				if not part.Parent:FindFirstChild("RenderObjectValue") then
					renderhumanoid = VF_Handler:RenderHumanoid(part.Parent,workspace.Commands.FPS.Value)
				end
			end
		end
	end

	for i, part in ipairs(lastParts) do
		if not table.find(parts, part) then
			table.insert(partsRemoved, part) -- this part was removed
			if part:FindFirstChild("RenderObjectValue") then
				if part.RenderObjectValue.Value ~= nil then
				part.RenderObjectValue.Value:Destroy()
					part.RenderObjectValue:Destroy()
				end
			end
			if part.Parent:FindFirstChildOfClass("Humanoid") then
				if part.Parent:FindFirstChild("RenderObjectValue") then
					part.Parent.RenderObjectValue.Value:Destroy()
					part.Parent.RenderObjectValue:Destroy()
				end
				end
		end
	end

	lastParts = parts -- save the parts from the current iteration to be contrasted with parts from the next iteration

	-- now, partsAdded will be a table of parts that are new
	-- partsRemoved will be a table of parts that have been removed since the last iteration
	wait(0.5)
end

basically render humanoid and render part just clones the part into the viewport as well as making an object value, which the object values value is the clone in the viewport in the module. btw, I know im using alot of if statements, I just find it more better.

[Ziraun]

before running the next if statement checking the parent’s parent, check if it even exists. its possible you’ve gone so far up the ancestry of the object you’re referencing that there are no more parents to reference.