WowAce

Recently got around to updating WoW to 7.1 followed by updating all the addons I have installed. After logging in-game as soon as the cursor passes over another player character VisualHeal generates the following error:

["message"] = "Interface\\AddOns\\VisualHeal\\VisualHeal.lua:675: Usage: UnitGUID(\"unit\")",
["count"] = 22,
["addons"] = "  MoncaiCompare, v7.0.1\n  Swatter, v7.0.3 (<%codename%>)\n  WowheadLooter, v60014\n  AckisRecipeList, v7.0.3.8\n  ACP, v3.4.30 \n  AdvancedInterfaceOptions, v1.0.6\n  AllPlayed, vv70100-1\n  AraBrokerReputations, vr18\n  ArcanaExperienceBroker, v70100.3.2\n  Armory, vv14.0.0\n  ArmoryGuildBank, vv14.0.0\n  Atlas, v1.35.04\n  AtlasArena, v1.06.03\n  AtlasBattlegrounds, v1.35.01\n  AtlasBurningCrusade, v1.35.01\n  AtlasCataclysm, v1.35.00\n  AtlasClassicWoW, v1.35.00\n  AtlasClassOrderHalls, v1.35.01\n  AtlasDungeonLocs, v1.35.00\n  AtlasLegion, v1.35.06\n  AtlasMistsofPandaria, v1.35.00\n  AtlasOutdoorRaids, v1.35.00\n  AtlasScenarios, v1.35.00\n  AtlasTransportation, v1.35.01\n  AtlasWarlordsofDraenor, v1.35.00\n  AtlasWorldEvents, v3.17\n  AtlasWrathoftheLichKing, v1.35.00\n  AtlasLoot, vv8.01.06\n  AtlasMajorCitiesEnhanced, vv1.11\n  AtlasQuest, v4.10.21\n  AutoGratzer, v2.0.2\n  BagMeters, v1.0.4\n  BasicBuffs, vv7.1.0\n  BattlePetDailyTamer, v2.1.2\n  BattlePetCount, v1.8.11\n  Bazooka, vv2.7.3\n  BrokerAFK, v2.8.6\n  BrokerCurrency, v7.0.3.2\n  BrokerGroup, v\n  BrokerPortals, v1.9.1\n  BrokerRecount, v1.0\n  BrokerReloadUI, v1.0.0\n  BrokeruClock, vv3.3.9\n  BrokerXPBar, v2.0 r058\n  BrokerMounts, v7.03\n  BrokerPets, v7.03\n  ButtonForge, v0.9.46\n  CanIMogIt, v7.1.0.02\n  Castbars, v\n  CloseUp, v7.1.001\n  CollectMe, v2.9.2\n  Cromulent, v70100-2\n  CTCore, v7.0.3.1\n  CTLibrary, v7.0.3.2\n  CTMailMod, v7.0.3.2\n  CTPartyBuffs, v7.0.3.1\n  DejaCharacterStats, v7.1.0 r3\n  EmoteLDB, v70100-1.2\n  Examiner, v16.08.30\n  FBBroker, v1.28\n  FBOutfitDisplayFrame, v1.7.11\n  FBTrackingFrame, v1.7.11\n  FishingBuddy, v1.7.11\n  FlightMap, v7.0.0.6\n  FlyoutButtonCustom, v2.76\n  Frenemy, v7.0.3.6\n  GatherMate2, v1.38.1\n  GatherMateSharing, vv1.10\n  GatherSage2, v20101207\n  GFWDisenchantPredictor, v5.2\n  Grail, v083\n  GrailAchievements, v011\n  GrailQuestsenUS, v22810\n  GrailReputations, v007\n  GrailWhen, v001\n  HandyNotes, vv1.4.11\n  HandyNotesDraenorTreasures, v1.20a\n  HandyNotesGuild, v1.9\n  HandyNotesLegionRaresTreasures, v1.01b\n  HandyNotesLostAndFound, v1\n  HandyNotesTimelessIsleChests, v1.16\n  ILearnedWhat, v7.0.01\n  InFlightLoad, v7.1.001\n  Juggler, v5.0.0.1\n  LightHeaded, vwowi:revision\n  LootToasts, v7.0.3.1\n  lsToasts, v1.20\n  MailNotifier, v\n  MailNotifierBroker, v\n  Mapster, v1.7.4\n  MasterPlanA, vA\n  Mendeleev, v3.0\n  MobInfo2, v7.1.0.001\n  oGlow, v2.2.5\n  Overachiever, v0.98\n  PetBattleTeams, v3.3.2\n  PetJournalEnhanced, v2.9.22\n  PlayerLinkMenu, v1.10\n  Prat30, vr1048      \n  Prat30Libraries, v\n  QuestProgressSound, v1.23\n  QuitConfirmed, v1.1\n  Rarity, v1.0\n  RarityOptions, v\n  Recount, vr1398\n  RepairBroker, v7.1.0\n  shPerformance, v\n  SilverDragon, vv3.2.9\n  TipTac, v16.10.27\n  TipTacItemRef, v16.10.27\n  TipTacTalents, v16.10.27\n  Toaster, v7.0.3.2\n  TomTom, vv70100-1.1.0-49459b0\n  TravelAgent, v7.1.0.1\n  TrinketMenu, v7.0.0\n  UnitFramesPlus, v1.26.1\n  VisualHeal, v\n  Volumizer, v7.0.3.1\n  Wholly, v060\n  xanAchievementMover, v1.9\n  BlizRuntimeLib_enUS v7.1.0.70100 <none>\n  (ck=ba5)\n",
["locals"] = "(*temporary) = nil\n",
["timestamp"] = "2016-11-29 20:12:29",
["context"] = "Global",
["stack"] = "[C]: in function `UnitGUID'\nInterface\\AddOns\\VisualHeal\\VisualHeal.lua:675: in function `UNIT_HEALTH'\nInterface\\AddOns\\VisualHeal\\VisualHeal.lua:683: in function `?'\nInterface\\AddOns\\VisualHeal\\VisualHeal.lua:3: in function <Interface\\AddOns\\VisualHeal\\VisualHeal.lua:3>\n",

I've logged in-game with all of my characters and this error occurs the first time the cursor passes over another player character. If I then clear the Swatter log the error will occur again the next time the cursor passes over another player character. Somewhat surprised that no-one else has reported this which makes me wonder if I've missed some sort of update on the future of VisualHeal.