Script saying there is a 'nil' value in this script, can someone help?

I am trying to create a script that makes a data storage for a player when he/she joins the game and update their health every second inside another IntValue, but the script is saying that there is a 'nil' value in the script.

local plr = game.Players.LocalPlayer


plr.CharacterAdded:connect(function(char)
	local Humanoid = char:WaitForChild('Humanoid')
	local plrName = plr.Name
	local PlayerData = game.ServerStorage.PlayerNameStorage:WaitForChild(plrName.."Data")
	local PlayerNameValue = PlayerData:WaitForChild(plrName.."NameValue")
	local HealthIntValue = PlayerData:WaitForChild(plrName.."HealthValue")
	local MaxHealthIntValue =PlayerData:WaitForChild(plrName.."MaxHealthValue")
	while true do
		if plr ~= nil then
			if char ~= nil then
				if Humanoid ~= nil then
					if Humanoid.Health > 0 then
						HealthIntValue.Value = Humanoid.Health
						wait(1)
					elseif Humanoid.Health <= 0 then
						HealthIntValue.Value = 0
						wait(1)
					end
				elseif Humanoid == nil then
					print("'Humanoid' not found; all relating objects removed.")
				end
			elseif char == nil then
				print("'char' not found; all relating objects removed.")
			end
		elseif plr == nil then
			print("'plr' not found; all relating objects removed.")				
		end
	end	
end)

Here is the whole code:

game.Players.PlayerAdded:connect(function(plr)
	local plrName = plr.Name
	if game.ServerStorage.PlayerNameStorage ~= nil then
		local PlayerData = Instance.new('Folder')
		PlayerData.Parent = game.ServerStorage.PlayerNameStorage
		PlayerData.Name = plrName.."Data"
		local PlayerNameValue = Instance.new('StringValue')
		PlayerNameValue.Parent = PlayerData
		PlayerNameValue.Name = plrName.."NameValue"
		PlayerNameValue.Value = plrName
		local HealthIntValue = Instance.new('IntValue')
		HealthIntValue.Parent = PlayerData
		HealthIntValue.Name = plrName.."HealthValue"
		local MaxHealthIntValue = Instance.new('IntValue')		
		MaxHealthIntValue.Name = plrName.."MaxHealthValue"
		MaxHealthIntValue.Parent = PlayerData
		plr.CharacterAdded:connect(function(char)
			local Humanoid = char:WaitForChild('Humanoid')
			if Humanoid.Health > 0 then
				HealthIntValue.Value = Humanoid.Health
				MaxHealthIntValue.Value = Humanoid.MaxHealth
			end
		end)
	end
end)

game.Players.PlayerRemoving:connect(function(plr)
	local plrName = plr.Name
	if game.ServerStorage.PlayerNameStorage:FindFirstChild(plrName.."Data") ~= nil then
		local PlayerData = game.ServerStorage.PlayerNameStorage:FindFirstChild(plrName.."Data")
		PlayerData:Destroy()
	end
end)


local plr = game.Players.LocalPlayer


plr.CharacterAdded:connect(function(char)
	local Humanoid = char:WaitForChild('Humanoid')
	local plrName = plr.Name
	local PlayerData = game.ServerStorage.PlayerNameStorage:WaitForChild(plrName.."Data")
	local PlayerNameValue = PlayerData:WaitForChild(plrName.."NameValue")
	local HealthIntValue = PlayerData:WaitForChild(plrName.."HealthValue")
	local MaxHealthIntValue =PlayerData:WaitForChild(plrName.."MaxHealthValue")
	while true do
		if plr ~= nil then
			if char ~= nil then
				if Humanoid ~= nil then
					if Humanoid.Health > 0 then
						HealthIntValue.Value = Humanoid.Health
						wait(1)
					elseif Humanoid.Health <= 0 then
						HealthIntValue.Value = 0
						wait(1)
					end
				elseif Humanoid == nil then
					print("'Humanoid' not found; all relating objects removed.")
				end
			elseif char == nil then
				print("'char' not found; all relating objects removed.")
			end
		elseif plr == nil then
			print("'plr' not found; all relating objects removed.")				
		end
	end	
end)