# Helper function to display an error on a node.
	# Alias for `self.toolcontext.error(n.hot_location, text)`
	#
	# This automatically sets `n.is_broken` to true.
	fun error(n: nullable ANode, text: String)
	do
		var l = null
		if n != null then
			l = n.hot_location
			n.is_broken = true
		end
		self.toolcontext.error(l, text)
	end