catch some error conditions

functions.lua

@@ -830,6 +830,16 @@ yl_speak_up.get_fs_edit_option_dialog = function(player, n_id, d_id, o_id)
 	local n_dialog = dialog.n_dialogs[d_id]
 	local d_option = n_dialog.d_options[o_id]
 
+	-- currently no trade running (we're editing options)
+	yl_speak_up.trade[pname] = nil
+	yl_speak_up.speak_to[pname].trade_id = nil
+
+	if(not(d_option)) then
+		return "size[6,2]"..
+			"label[0.2,0.5;Ups! Option "..minetest.formspec_escape(tostring(o_id))..
+				" does not exist.]"..
+			"button_exit[2,1.5;1,0.9;exit;Exit]"
+	end
 	-- are there any preconditions?
 	local list_of_preconditions = ""
 	local prereq = d_option.o_prerequisites
@@ -1088,6 +1098,10 @@ yl_speak_up.get_fs_talkdialog = function(player, n_id, d_id)
         return get_error_message()
     end
 
+    -- currently no trade running (we're editing options)
+    yl_speak_up.trade[pname] = nil
+    yl_speak_up.speak_to[pname].trade_id = nil
+
     --[[ If we have an explicit call for a certain d_id, we grab it from parameters. 
     If not, we grab in from context. 
     When neither are present, we grab it from d_sort
@@ -1826,6 +1840,7 @@ yl_speak_up.show_fs = function(player, fs_name, param)
 	-- "confirm_save" does not have its own option here; doesn't have a get_fs_-function either
 
 	elseif(fs_name == "edit_option_dialog") then
+		-- the optional "caller" parameter can be used for debugging
 		if(not(param)) then
 			param = {}
 		end
@@ -2751,7 +2766,8 @@ yl_speak_up.input_edit_option_dialog = function(player, formname, fields)
 	-- if a new option was added or the target dialog of this one changed, display the right new option
 	if(result and result["show_next_option"] and n_dialog.d_options[result["show_next_option"]]) then
 		yl_speak_up.show_fs(player, "edit_option_dialog",
-			{n_id = n_id, d_id = d_id, o_id = result["show_next_option"]})
+			{n_id = n_id, d_id = d_id, o_id = result["show_next_option"],
+			 caller="show_next_option"})
 		return
 	end
 
@@ -2784,7 +2800,7 @@ yl_speak_up.input_edit_option_dialog = function(player, formname, fields)
 		end
 		-- show that dialog; fallback: show the same (o_id) again
 		yl_speak_up.show_fs(player, "edit_option_dialog",
-			{n_id = n_id, d_id = d_id, o_id = o_found})
+			{n_id = n_id, d_id = d_id, o_id = o_found, caller="prev option"})
 		return
 
 	-- the player wants to see the next option/answer
@@ -2799,7 +2815,7 @@ yl_speak_up.input_edit_option_dialog = function(player, formname, fields)
 		end
 		-- show that dialog; fallback: show the same (o_id) again
 		yl_speak_up.show_fs(player, "edit_option_dialog",
-			{n_id = n_id, d_id = d_id, o_id = o_found})
+			{n_id = n_id, d_id = d_id, o_id = o_found, caller="next option"})
 		return
 
 	-- show the trade associated with this dialog and option
@@ -3080,7 +3096,7 @@ yl_speak_up.input_talk = function(player, formname, fields)
 				 or fields["effects_"..o_id]) then
 					yl_speak_up.show_fs(player, "edit_option_dialog",
 						{n_id = yl_speak_up.speak_to[pname].n_id,
-						 d_id = d_id, o_id = o_found})
+						 d_id = d_id, o_id = o_id, caller="button"})
 					return
 				end
 			end