Why is my loop randomly stopping and stopping the rest of the script?

I have a chest unlocking system. Here is the code. unlock is the BillboardGui shown while unlocking. items is a table of items the chest can pick from.

local plr = script.Parent.Parent.Parent.Parent.Parent
local data = plr:WaitForChild("PlayerData")
local DS = game:GetService("DataStoreService"):GetDataStore("GameData")
local purchases = DS:GetAsync("ShovelsBought")
local itemdata = script.Parent.Parent.Parent.Items:FindFirstChild(script.Parent.Parent.itemName.Value)

script.Parent.MouseButton1Click:connect(function()
	if data.Leaderstats.Currency.Value >= itemdata.Price.Value then
		purchases = purchases + 1
		DS:SetAsync("ShovelsBought",purchases)
		purchases = DS:GetAsync("ShovelsBought")
		data.Leaderstats.Currency.Value = data.Leaderstats.Currency.Value - itemdata.Price.Value
		-- For use with shovels.  This part works fine.  Scroll to the line where it says itemdata.Type.Value == "Crate".
		if itemdata.Type.Value == "Shovel" or itemdata.Type.Value == "Trail" then
		local newitem = data.Inventory.Basic:Clone()
		newitem.Name = script.Parent.Parent.itemName.Value
		newitem.Value = true
		newitem.Parent = data.Inventory
		local scr = script.Parent.Parent.Parent.Frame.Scripts.Equip:Clone()
		scr.Parent = script.Parent
		scr.Disabled = false
		script.Parent.Text = "Equip"
		script:Destroy()
		elseif itemdata.Type.Value == "Crate" then --Starts here.
			local items = {} --Table for containing possible chest items
			
			for _,v in pairs(itemdata:GetChildren()) do
				if v.Name == "ChestItem" then
					table.insert(items,v) --Inserts all chest items into the table.
				end
			end
			local unlock = game.ServerStorage.UnlockingIcon:Clone() --Makes the Billboardgui
			unlock.Parent = plr.Character.Head
			--[[for i = 1,12 do --Temporarily noted.  This works fine.
				print("0a"..i)
				unlock.ExtentsOffset = unlock.ExtentsOffset + Vector3.new(0,0.5,0)
				wait(0.2)
			end]]
			local runs = 0
			for i = 1,30 do --This is where problem starts.
				local tempitem = items[math.random(1,#items)].Value
				runs = runs +1
				unlock.Frame.ItemImg.Image = "rbxassetid://"..tempitem.ImageId.Value
				print(runs)
				wait(0.15)
			end
			print(2)
		end
	end
end)

The problem is, the loop is randomly stopping, and stopping the rest of the script. I added runs for debugging purposes, and each time I run it, I see it stop at a random number, then the rest of the script doesn't run.

For instance: Run 1 output:

1
2
3
4
5

Run 2 output:

1
2
3

Etc. Any help?