Workaround for sign regression with 5.12.0

---------

Co-authored-by: sfan5 <[email protected]>
Co-authored-by: Lars Müller <[email protected]>

Author: 3 people

mods/default/nodes.lua

@@ -2604,6 +2604,9 @@ local function register_sign(material, desc, def)
 			meta:set_string("formspec", "field[text;;${text}]")
 		end,
 		on_receive_fields = function(pos, formname, fields, sender)
+			if not fields.quit then
+				return -- workaround for https://github.com/luanti-org/luanti/issues/16187
+			end
 			local player_name = sender:get_player_name()
 			if minetest.is_protected(pos, player_name) then
 				minetest.record_protection_violation(pos, player_name)