The Parent property of "Block" is locked?

This script has been working for so long now, now its saying an error:

The Parent property of RjsMcCar is locked, current parent: NULL, new parent Workspace <

local c1cost = 10000
local reb = 2
local player = game.Players.LocalPlayer
local leaderboard = player:WaitForChild("Values")
print(workspace:FindFirstChild(player.Name.."Car"))
script.Parent.Text = "Crest - "..c1cost.." | Rebirth 2"



local c1 = game.ReplicatedStorage.Cars["Crest"]:Clone() --Car





script.Parent.MouseButton1Click:connect(function()
	local search = workspace:FindFirstChild(player.Name.."Car")
	if (leaderboard.Coins.Value >= c1cost and leaderboard.Rebirth.Value >= 2) then
		if search == nil then
			script.Parent.Text = "Spawning Car..."
			wait(1)
			script.Parent.Text = "Crest - "..c1cost.." | Rebirth "..reb
			script.Parent.Parent.Parent.Parent:TweenPosition(UDim2.new(0.02, 0,1.004, 0), "Out", "Quad", 1, false, nil)
		c1.Name = player.Name.."Car"
		c1:MakeJoints()
		c1.Parent = game.Workspace --I think the error is here | The Parent property of RjsMcCar is locked, current parent: NULL, new parent Workspace


		c1:MoveTo(player.Character.Torso.Position + Vector3.new(10, 0, 0))
		else
			
			
			
			
			
			search:Destroy()
			script.Parent.Text = "Previous Car Removed... Spawning Car"
			wait(1)
			script.Parent.Text = "Crest - "..c1cost.." | Rebirth "..reb
			script.Parent.Parent.Parent.Parent:TweenPosition(UDim2.new(0.02, 0,1.004, 0), "Out", "Quad", 1, false, nil)
		c1.Name = player.Name.."Car"
		c1.Parent = game.Workspace
		c1:MakeJoints()
		c1:MoveTo(player.Character.Torso.Position + Vector3.new(10, 0, 0))
		end
		
		
		
		
	else
		if leaderboard.Rebirth.Value >= 2 then
			script.Parent.Text = "Need $"..c1cost - leaderboard.Coins.Value
			wait(1)
			script.Parent.Text = "Crest - "..c1cost.." | Rebirth "..reb
		else
			script.Parent.Text = "Need Rebirth "..reb
			wait(1)
			script.Parent.Text = "Crest - "..c1cost.." | Rebirth "..reb
		end
	end
end)