0 Old game no longer works due to the removal of Experimental Mode what needs to be added?

I am trying to track down (and it has been 2 years so learning all of this again) what I need to do to fix this script (I bet more are like this one).

local wspace = game.Workspace
local rumble = wspace.RumbleSoundPart
local magnitude = 0
local temp = 0
local temp2 = 0
local maxdistance = 18
while true do
	wait(0.5)
	for i,v in pairs(game.Players:GetChildren()) do
magnitude = ((v.Character.Head.Position - wspace.RumbleSoundPart.Position).magnitude) - 4
if magnitude < 1 then magnitude = 1 end
temp = (magnitude/maxdistance)
if temp > 0.4 then temp = 0.4 end
temp2 = 1 - temp
if temp2 > 0.4 then temp2 = 0.4 end
if temp2 < 0 then temp2 = 0 end
wspace.MusicScript.Sound.Volume = temp
wspace.MusicScript.Sound1.Volume = temp
wspace.MusicScript.Sound2.Volume = temp
wspace.RumbleSoundPart.Sound.Volume = temp2
	end
end

Error is Attempt to index field 'Character' (a nil value). What should I add to make sure the character is in the game before this gets called? I tried a few things but nothing seemed to work.

Use the CharacterAdded event of a player to get a reference to their character when it's replicated.

ex:

game.Players.PlayerAdded:Connect(function(player)
	player.CharacterAdded:Connect(function(character)
		-- Character is returned from the CharacterAdded event so you can just include it in the callback function as a parameter 
	end)
end)

local wspace = game.Workspace 
local rumble = wspace.RumbleSoundPart 
local magnitude = 0 
local temp = 0 
local temp2 = 0 
local maxdistance = 18 
while wait(0.5) do  
	for i,v in pairs(game.Players:GetChildren()) do 
		if not v.Character then
			repeat
				wait()
			until v.Character
		end
		v.Character:WaitForChild("Head")
		magnitude = ((v.Character.Head.Position - wspace.RumbleSoundPart.Position).magnitude) - 4 
		if magnitude < 1 then 
			magnitude = 1 
		end 
		temp = (magnitude/maxdistance) 
		if temp > 0.4 then 
			temp = 0.4 
		end 
		temp2 = 1 - temp 
		if temp2 > 0.4 then 
			temp2 = 0.4 
		end 
		if temp2 < 0 then 
			temp2 = 0 
		end 
		wspace.MusicScript.Sound.Volume = temp 
		wspace.MusicScript.Sound1.Volume = temp 
		wspace.MusicScript.Sound2.Volume = temp 
		wspace.RumbleSoundPart.Sound.Volume = temp2 
		--sf=string.format 
		--print(sf("temp is %f, temp2 is %f, magnitude is %f",temp, temp2, magnitude)) 
	end 
end

To wait for the character, you first have to make sure that the character isn't nil, and if it is, wait for it using a repeat-until loop. After that, you want to wait for all parts of the character to be added, hence the Character:WaitForChild("Head").