What is the issue? Bug.

Date: 2008-09-01 16:13:01
ID: 53
Error occured in: Global
Count: 1
Message: ..\AddOns\QuestHelper\graph.lua line 185:
   attempt to compare nil with number
Debug:
   [C]: ?
   QuestHelper\graph.lua:185 AddRouteStartNode()
   QuestHelper\pathfinding.lua:163 ComputeRoute()
   QuestHelper\dodads.lua:661
      QuestHelper\dodads.lua:636
AddOns:
  AckisRecipeList, v0.936
  Auctioneer, v5.0.PRE.3342
  Bartender3, v3.1.2 r78566
  BonusScanner, v3.5
  Cartographer, vr73088
  CartographerCleanup, v1.0
  CartographerData, v1.0
  CartographerHerbalism, v1.0
  CartographerMailboxes, v1.0
  CartographerMining, v1.0
  CartographerNoteHere
  CartographerQuestInfo, v1.9.20
  CartographerFishing, v1.0
  CartographerHotspot, v1.32
  CartographerIcons, v1.0
  CartographerIconsBlizzardPack, v1.0
  CartographerIconsCtMapModPack, v1.0
  CartographerIconsFancyPack, v1.0
  CartographerIconsGathererPack, v1.0
  CartographerIconsMetaMapPack, v1.0
  CartographerIconsNumbers, v1.0
  CartographerImport, v1.0
  CartographernnTrainers, v1
  CartographerNoteshare, v1.0
  CartographerNoteTarget, v0.3
  CartographerQuestObjectives, v0.9b
  CartographerQuests, v0.2
  CartographerQuicknotes, v0.1
  CartographerRoutes, v1.0
  CartographerStats, v1.0
  CartographerTreasure, v1.0
  Chinchilla, v1.0r77817
  DruidStats, v0.9.6
  Enchantrix, v5.0.PRE.3342
  EnhTooltip, v5.0.PRE.3342
  FishingBuddy, v0.9.4m
  GatherMate, v1.0
  GatherMateCartImport, v1.0
  GatherMateSharing, v1.0
  HandyNotes, v1.0
  HandyNotesMailboxes, v1
  HandyNotesStables, v1
  HealBot, v2.4.3.9
  InFlight, v2.4.010
  InFlightLoad, v2.4.006
  Informant, v5.0.PRE.3342
  Ace2
  Ace3
  Babble22, v2.2.$Revision: 66632 $
  LibBabbleCreatureType30
  LibBabbleInventory30
  ChatThrottleLib, v19
  LibGratuity30, vr$Revision: 41183 $
  LibRock10
  PersonalSentry, v1.60b
  QuestHelper, v0.48
  ReagentRestocker, v0.9c
  RecipeRadar, v1.24
  RecipeKnown, v0.113b.20400
  Routes, v1.0
  SpamEraser
  Stubby, v93
  Swatter, v5.0.PRE.3342
  TitanHonorView, v2.00
  TitanAmmo, v3.2.6.20400
  TitanBag, v3.2.6.20400
  TitanClock, v3.2.6.20400
  TitanCoords, v3.2.6.20400
  TitanGoldTracker, v3.2.6.20400 (2.3.2)
  TitanHonorGrindFanUpdate, v3.1.20400
  TitanHonor, v3.2.6.20400 (1.13)
  TitanItemBonuses, v3.2.6.20400
  TitanLootType, v3.2.6.20400
  TitanPerformance, v3.2.6.20400
  TitanRegen, v3.2.6.20400
  TitanRepair, v3.2.6.20400
  TitanRider, v3.2.6.20400
  TitanStanceSets, v3.2.6.20400
  TitanXP, v3.2.6.20400
  Titan, v3.2.6.20400
  WeaponQuickSwap

Please provide any additional information below.
I was flying from Darnassus to Winterspring.