So basically I only have errors when I add script.parent.Mousebutton1click can someone help?

script.Parent.MouseButton1Click:Connect(function()
	local plr = game.Players.LocalPlayer
	local mouse = plr:GetMouse()

	local player = plr

	if workspace:FindFirstChild("Core") then workspace.Core:Destroy() end
 
	local Core = Instance.new("Part") Core.Name = "Core" Core.Size = Vector3.new(0.05, 0.05, 0.05)

	spawn(function() Core.Parent = workspace local Weld = Instance.new("Weld", Core) Weld.Part0 = Core Weld.Part1 = localplayer.Character.LowerTorso Weld.C0 = CFrame.new(0, 0, 0) end)

	workspace:WaitForChild("Core")

	local torso = workspace.Core 
	flying = true 
	local speed=10
	local keys={a=false,d=false,w=false,s=false}
	local e1
	local e2 
	local function start()
		local pos = Instance.new("BodyPosition",torso)
		local gyro = Instance.new("BodyGyro",torso)
		pos.Name="EPIXPOS"
		pos.maxForce = Vector3.new(math.huge, math.huge, math.huge)
		pos.position = torso.Position
		gyro.maxTorque = Vector3.new(9e9, 9e9, 9e9)
		gyro.cframe = torso.CFrame
		repeat wait()
			player.Character.Humanoid.PlatformStand=true 
			local new=gyro.cframe - gyro.cframe.p + pos.position 
			if not keys.w and not keys.s and not keys.a and not keys.d then
				speed=5
			end
			if keys.w then 
				new = new + workspace.CurrentCamera.CoordinateFrame.lookVector * speed 
				speed=speed+0
			end 
			if keys.s then 
				new = new - workspace.CurrentCamera.CoordinateFrame.lookVector * speed 
				speed=speed+0
			end 
			if keys.d then 
				new = new * CFrame.new(speed,0,0) 
				speed=speed+0
			end 
			if keys.a then 
				new = new * CFrame.new(-speed,0,0)
				speed=speed+0
			end
			if speed>10 then
				speed=5 
			end
			pos.position=new.p 
			if keys.w then 
				gyro.cframe = workspace.CurrentCamera.CoordinateFrameCFrame.Angles(-math.rad(speed0),0,0)
			elseif keys.s then
				gyro.cframe = workspace.CurrentCamera.CoordinateFrameCFrame.Angles(math.rad(speed0),0,0)
			else
				gyro.cframe = workspace.CurrentCamera.CoordinateFrame 
			end 
		until flying == false 
		if gyro then 
			gyro:Destroy()
		end 
		if pos then
			pos:Destroy()
		end 
		flying=false 
		player.Character.Humanoid.PlatformStand=false
		speed=10 
	end
	e1=mouse.KeyDown:connect(function(key) 
		if not torso or not torso.Parent then 
			flying=false
			e1:disconnect()
			e2:disconnect()
			return
		end
		if key=="w" then 
			keys.w=true
		elseif key=="s" then 
			keys.s=true 
		elseif key=="a" then 
			keys.a=true
		elseif key=="d" then 
			keys.d=true 
		elseif key=="x" then 
			if flying==true then
				flying=false 
			else 
				flying=true
				start()
			end
		end 
	end)
	e2=mouse.KeyUp:connect(function(key)
		if key=="w" then
			keys.w=false 
		elseif key=="s" then 
			keys.s=false 
		elseif key=="a" then
			keys.a=false
		elseif 
			key=="d"
		then 
			keys.d=false 
		end 
	end) 
	start()
end)

does this help you? you forgot an "end)" at the end of the code to close the mousebutton1click function also use code block and use the enter key for posting here, many people aren't used to just using 1 line to write a full code, and it's better to use the enter key so its easier to organize and the computer is happy when checking the code.