Fix error when opening certain dialogs (fixes #12)

Author: Numynum

main.lua

@@ -205,7 +205,7 @@ function DialogKey:OnGossipFrameUpdate(GossipFrame)
         if tag then
             if self.db.numKeysForGossip then
                 local oldText = data.info[tag]
-                if (FlagsUtil.IsSet(data.info.flags, Enum.GossipOptionRecFlags.QuestLabelPrepend)) then
+                if data.info.flags and FlagsUtil.IsSet(data.info.flags, Enum.GossipOptionRecFlags.QuestLabelPrepend) then
                     oldText = GOSSIP_QUEST_OPTION_PREPEND:format(oldText);
                 end
                 local newText = (n % 10) .. ". " .. (oldText:match("^%d. (.+)$") or oldText)