I logged into a character that doesn't have any guide loaded (and hasn't used WoWPro - yay for crafting alts) and got the following error:

Date: 2010-08-11 06:17:10
ID: 1
Error occured in: Global
Count: 1
Message: ..\AddOns\WoWPro\WoWPro_Mapping.lua line 37:
attempt to index field '?' (a nil value)
Debug:
(tail call): ?
WoWPro\WoWPro_Mapping.lua:37: MapPoint()
WoWPro\WoWPro.lua:86:
WoWPro\WoWPro.lua:65
(tail call): ?

[string "safecall Dispatcher[1]"]:9:
[string "safecall Dispatcher[1]"]:5
(tail call): ?
Ace3\AceAddon-3.0\AceAddon-3.0.lua:539: EnableAddon()
Ace3\AceAddon-3.0\AceAddon-3.0.lua:629:
Ace3\AceAddon-3.0\AceAddon-3.0.lua:615

..\FrameXML\UIParent.lua:235: UIParentLoadAddOn()
..\FrameXML\UIParent.lua:258: CombatLog_LoadUI()
..\FrameXML\UIParent.lua:482:
..\FrameXML\UIParent.lua:454
AddOns:
Swatter, v5.8.4723 (CreepyKangaroo)
Ace3, v
AcherusLoader, v
AucAdvanced, v5.8.4723 (CreepyKangaroo)
AucFilterBasic, v5.8.4723 (CreepyKangaroo)
AucFilterOutlier, v5.8.4723.2531
AucMatchUndercut, v5.8.4723.2531
AucStatHistogram, v5.8.4723 (CreepyKangaroo)
AucStatiLevel, v5.8.4723 (CreepyKangaroo)
AucStatPurchased, v5.8.4723 (CreepyKangaroo)
AucStatSales, v5.8.4723.2842
AucStatSimple, v5.8.4723 (CreepyKangaroo)
AucStatStdDev, v5.8.4723 (CreepyKangaroo)
AucStatWOWEcon, v5.8.4723.2530
AucUtilAHWindowControl, v5.8.4723.3311
AucUtilAppraiser, v5.8.4723.2530
AucUtilAskPrice, v5.8.4723.3175
AucUtilAutoMagic, v5.8.4723.3142
AucUtilCompactUI, v5.8.4723.2530
AucUtilEasyBuyout, v5.8.4723.3583
AucUtilGlypher, v5.8.4723.2545
AucUtilItemSuggest, v5.8.4723.3108
AucUtilPriceLevel, v5.8.4723.2545
AucUtilScanButton, v5.8.4723.2530
AucUtilScanFinish, v5.8.4723.3576
AucUtilScanProgress, v5.8.4723.2530
AucUtilScanStart, v5.8.4723.2530
AucUtilSearchUI, v5.8.4723.3655
AucUtilSimpleAuction, v5.8.4723.4546
AucUtilVendMarkup, v5.8.4723.2530
AuctionLite, v1.6.4
Bartender4, v4.4.2
BeanCounter, v5.8.4723 (CreepyKangaroo)
clcbpt, v2.0
Combuctor, v2.2.2
CombuctorSets, v
Configator, v5.1.DEV.130
DBMCore, v
ElitistGroup, v
Gatherer, v3.1.14
kgPanels, vv1.5.2
LauncherMenu, vv1.2
LeatrixGfx, v
Livestock, v1.2.2
LoadIT, v
MinimapButtonFrame, v3.1.0
MTarget, v2.0.1
Multishot, vr41
Omen, v3.0.9
OmniCC, v2.5.9
Outfitter, v5.0b8
pMinimap, v30300.8-Release
Postal, v3.3.2
PowerAuras, v3.0.0K
Quartz, v3.0.3.1
RaidLeader, v0.1
RatingBuster, v
Recount, v
SatrinaBuffFrame, v3.1
sct, v6.2
ShadowedUFIndicators, v
ShadowedUnitFrames, vv3.2.12
SLDataText, v3.1.4
SlideBar, v5.8.4723 (CreepyKangaroo)
Stubby, v5.8.4723 (CreepyKangaroo)
teksLoot, v3.3.0.9
TidyPlates, v5.12.3
TidyPlatesGrey, v
TidyPlatesThreatPlates, v3.0.4
TomTom, vwowi:revision
WIM, v3.3.7
WoWPro, v1.0.0
WoWProLeveling, v1.0.0
YssDrop, vv1.8.10
BlizRuntimeLib_enUS v3.3.5.30300
(ck=820)

Which equates to this line:

zone = zone or zonenames[zc][zi]

This is using the latest from git. I'm guessing something hasn't been initiialised - but should it also not be calling the mapping functions if there is no map points (given this is the nil guide)?

Yeah, thought I got this logic set up but apparently not. Will go over it and fix.

Resolved, I think.