How do you wait for one function of two functions to fire?

I searched this question on google, but instead, showed me how to FIRE multiple functions and not WAIT for multiple functions to fire.

My goal is to see if a function fired out of two functions. If both functions fired at the same time somehow, then it will continue the program. If one function fires, but not the other, then it will continue the program. If no functions fire, then keep waiting for one of them to fire.

Here's the code:

local guiPopUpEvent = game.ReplicatedStorage.OpenIslandThingyThingThing
local guiClosedEvent = game.ReplicatedStorage.CloseIslandThingyThingThing
local islandSwitchGUI = script.Parent
local click = islandSwitchGUI.Click

guiPopUpEvent.OnClientEvent:Connect(function(plr)
	if not islandSwitchGUI.Enabled then
		islandSwitchGUI.Enabled = true
		
		click:Play()
		
		spawn(islandSwitchGUI.Close.CloseButton.MouseButton1Click:Wait())
		spawn(islandSwitchGUI.GO.Button.MouseButton1Click:Wait())
		
		-- Continue program
	end
end)

I got this error when it ran:

Spawn function requires 1 argument - Client - Show&Hide:12

(Show&Hide is the script name)

I did this:

local guiPopUpEvent = game.ReplicatedStorage.OpenIslandThingyThingThing
local guiClosedEvent = game.ReplicatedStorage.CloseIslandThingyThingThing
local islandSwitchGUI = script.Parent
local click = islandSwitchGUI.Click

guiPopUpEvent.OnClientEvent:Connect(function(plr)
	if not islandSwitchGUI.Enabled then
		islandSwitchGUI.Enabled = true
		
		click:Play()
		
		local closed = false
		
		while not closed do
			islandSwitchGUI.Close.CloseButton.MouseButton1Click:Connect(function()
				closed = true
			end)
			
			if not closed then
				islandSwitchGUI.GO.Button.MouseButton1Click:Connect(function()
					closed = true
				end)
			end
			wait()
		end
		
		-- Continue program
	end
end)

Thanks for trying to help!

Well you should probably learn how to use coroutines.

You can maybe try this:

-- at the start
local condition1 = false
local condition2 = false
islandSwitchGUI.Close.CloseButton.MouseButton1Click:Connect(function()
	condition1 = true
end)
islandSwitchGUI.GO.Button.MouseButton1Click:Connect(function()
	condition2 = true
end)

-- lines twelve and thirteen, replace with
repeat wait() until condition1 or condition2