This script has multiple errors not in output and I don't know why?

This code is supposed to make a brick spawn every 10 seconds on a brick spawner (which it is parented under), with a slight chance of being a golden brick, and the brick is given an IntValue. Past bricks are supposed to be deleted.

The two problems I faced:

Multiple bricks spawn at a time

Past bricks are not deleted

Code:

while wait(10) do
	for i,v in pairs(script.Parent:GetChildren())do
		if v.Name == "Brick" then
			v:Destroy()
		else
			bval = math.random(1,100)
			if bval <= 99 then
				brick = Instance.new("Part", script.Parent)
				brick.Position = script.Parent.Position
				brick.Size = Vector3.new(2,0.5,1)
				brickval = Instance.new("IntValue")
				brickval.Value = 1
			elseif bval == 100 then
				brick = Instance.new("Part", script.Parent)
				brick.Position = script.Parent.Position
				brick.Size = Vector3.new(2,0.5,1)
				brick.BrickColor = BrickColor.new("New Yeller")
				sparkles = Instance.new("Sparkles", brick)
				brickval = Instance.new("IntValue")
				brickval.Value = 25
			end
			
		end
	end
end

For the aftermath, the game can be visited here.

(I see you already figured it out, but) the way I'd do it is:

local brick, brickval, bval
while wait(10) do
    if brick then brick:Destroy() end -- Destroy the old part (if any)
    -- Make a new one
    brick = Instance.new("Part")
    brick.Size = Vector3.new(2,0.5,1)
    brick.Position = script.Parent.Position
    brickval = Instance.new("IntValue")
    bval = math.random(1, 100)
    if bval <= 99 then -- Normal
        brickval.Value = 1
    else -- Golden
        brick.BrickColor = BrickColor.new("New Yeller")
        brickval.Value = 25
        local sparkles = Instance.new("Sparkles")
        sparkles.Parent = brick
    end
    brickval.Parent = brick
    brick.Parent = script.Parent
end

Do note that Instance.new(part, parent) is deprecated - you're supposed to do .Parent after you've changed the other properties (especially Size and Position, which cause a bit of unnecessary lag if the part is already in the Workspace). This isn't a concern when you're only making 1 part every 10 seconds, but it's good practice nonetheless.

I changed the structure a bit so that the common code is outside the if block; you can see exactly what makes a brick normal/golden.