report multiple dialog results and refuse edit in such a disambigous case

functions.lua

@@ -2531,6 +2531,43 @@ minetest.register_on_player_receive_fields(
 )
 
 
+-- identify multiple results that lead to target dialogs
+yl_speak_up.check_for_disambigous_results = function(n_id, pname)
+	local errors_found = false
+	local dialog = load_dialog(n_id)
+	-- nothing defined yet - nothing to repair
+	if(not(dialog.n_dialogs)) then
+		return
+	end
+	-- iterate over all dialogs
+	for d_id, d in pairs(dialog.n_dialogs) do
+		if(d_id and d and d.d_options) then
+			-- iterate over all options
+			for o_id, o in pairs(d.d_options) do
+				if(o_id and o and o.o_results) then
+					local dialog_results = {}
+					-- iterate over all results
+					for r_id, r in pairs(o.o_results) do
+						if(r.r_type == "dialog") then
+							table.insert(dialog_results, r_id)
+						end
+					end
+					if(#dialog_results>1) then
+						minetest.chat_send_player(pname, "ERROR: Dialog "..
+							tostring(d_id)..", option "..tostring(o_id)..
+							", has multiple results of type dialog: "..
+							minetest.serialize(dialog_results)..". Please "..
+							"let someone with npc_master priv fix that first!")
+						errors_found = true
+					end
+				end
+			end
+		end
+	end
+	return errors_found
+end
+
+
 minetest.register_on_player_receive_fields(
     function(player, formname, fields)
         if formname ~= "yl_speak_up:talk" then
@@ -2637,6 +2674,13 @@ minetest.register_on_player_receive_fields(
                 minetest.chat_send_player(pname, "Sorry. You do not have the npc_talk_owner or npc_master priv.")
                 return
 	    end
+	    -- the staff allows to create multiple target dialogs as result; this makes no sense
+	    -- and is too disambigous
+	    if(yl_speak_up.check_for_disambigous_results(n_id, pname)) then
+                -- this needs to be fixed by someone with a staff; we don't know which dialog is the right
+		-- result
+                return
+            end
 	    -- enter edit mode with that particular NPC
             yl_speak_up.edit_mode[pname] = yl_speak_up.speak_to[pname].n_id
 	    -- start a new chat - but this time in edit mode