"transformation errored" error in value of `PlutoUI.combine()`

[Yuval]

As seen here:

using PlutoUI

md"""
 $x_opts_md
 $(@bind y CheckBox()) y
"""

begin
	n = Ref(0)		
	x_opts_md = @bind x_opts PlutoUI.combine() do Child
		md"""
		 $(Child("x", CheckBox())) x
		"""
	end
end

let
	n[] += 1
	x_opts, n
end

n here is not necessary to reproduce the bug, it just shows that multiple updates are triggered, between 1 and 3 on different runs. x_opts seem to contain the error only when n is 2.

(Pluto 0.9.40, PlutoUI 0.7.58, julia 1.9.3)

[Yuval]

On Chrome, this also happens with details:

details("parameters", @bind params PlutoUI.combine() do Child
	md"""
	 $(Child("x", CheckBox())) x
	"""
end)

(observed in Chrome on Windows and Mac, but doesn't seem to happen on Firefox, for details)