The game is spamming LUA-Errors. Any Idea what's the Problem here?

Thank you for reporting this.
Although I could not replicate this bug exactly I did find some irregularities in the previous version.
So please check out version 2.51.1. I hope your bug got fixed as well.

I still get THIS Error, but I can just close it without getting "spammed" with error Messages. The Addon seems to work.

Message: bad argument #1 to '?' (outside of expected range -2147483648 to 2147483647 - Usage: local name, spellID, icon, isActive, isUsable, sourceType, isFavorite, isFactionSpecific, faction, shouldHideOnCha
Time: Sat Sep 13 13:13:19 2025
Count: 1
Stack:
[C]: in function 'GetMountInfoByID'
[Interface/AddOns/MountJournalEnhanced/Favorites.lua]:30: in function 'pred'
[Interface/AddOns/Blizzard_SharedXMLBase/TableUtil.lua]:187: in function 'tFilter'
[Interface/AddOns/MountJournalEnhanced/Favorites.lua]:29: in function <Interface/AddOns/MountJournalEnhanced/Favorites.lua:25>
[Interface/AddOns/MountJournalEnhanced/Favorites.lua]:127: in function <Interface/AddOns/MountJournalEnhanced/Favorites.lua:118>
[C]: ?
[Interface/AddOns/Blizzard_SharedXMLBase/CallbackRegistry.lua]:144: in function <...e/AddOns/Blizzard_SharedXMLBase/CallbackRegistry.lua:143>
[C]: ?
[Interface/AddOns/Blizzard_SharedXMLBase/CallbackRegistry.lua]:147: in function 'TriggerEvent'
[Interface/AddOns/MountJournalEnhanced/MountJournalEnhanced.lua]:78: in function <...AddOns/MountJournalEnhanced/MountJournalEnhanced.lua:66>
[Interface/AddOns/MountJournalEnhanced/MountJournalEnhanced.lua]:87: in function <...AddOns/MountJournalEnhanced/MountJournalEnhanced.lua:85>
[C]: ?
[Interface/AddOns/Blizzard_SharedXMLBase/CallbackRegistry.lua]:144: in function <...e/AddOns/Blizzard_SharedXMLBase/CallbackRegistry.lua:143>
[C]: ?
[Interface/AddOns/Blizzard_SharedXMLBase/CallbackRegistry.lua]:147: in function 'TriggerEvent'
[Interface/AddOns/Blizzard_SharedXMLBase/GlobalCallbackRegistry.lua]:9: in function <...ns/Blizzard_SharedXMLBase/GlobalCallbackRegistry.lua:8>

Locals:
(*temporary) = "bad argument #1 to '?' (outside of expected range -2147483648 to 2147483647 - Usage: local name, spellID, icon, isActive, isUsable, sourceType, isFavorite, isFactionSpecific, faction, shouldHideOnChar, isCollected, mountID, isSteadyFlight = C_MountJournal.GetMountInfoByID(mountID))"

Oh, that's interesting. I think your addon settings got somehow a bit. There seems to be a value inside, which shouldn't be there.

Could you please copy (or screenshot) me, what this command says?

/dump MJEGlobalSettings.favorites.profiles[MJEGlobalSettings.favorites.assignments[UnitGUID("player")] or 1].mounts

The result should look somewhat like a simple list consisting only of numbers.

Dump: value=MJEGlobalSettings.favorites.profiles[MJEGlobalSettings.favorites.assignments[UnitGUID("player")] or 1].mounts
 [1]={
   [1]=764,
   [2]=1458,
   [3]=2235,
   [4]=2140,
   [5]=2313,
 }

My guess is that another table or string got somehow mixed into it. The real issue is to find the cause for that.

If that is the case, you could reset your favorites by using the "Uncheck All" option in the favorites menu (aka Star button). However you need to set your favorites manually again.
With that your favorites get applied in the background again. So your random mount button should work as intended. Currently it shouldn't change favorites around when you're switching alts.

okay, where do I put the command? Not WoW Chat I guess (doesn't work) :-D

sorry, there was indeed a space too much in the upper post. 🙈 please try again.
and yes, it's a chat command.

 mountID=986 

},
[4]={
index=949,
mountID=949
},
[5]={
index=797,
mountID=797
},
[6]={
index=898,
mountID=898
},
[7]={
index=1008,
mountID=1008
},
[8]={
index=970,
mountID=970
},
[9]={
index=802,
mountID=802
},
[10]={
index=931,
mountID=931
},
[11]={
index=656,
mountID=656
},
[12]={
index=975,
mountID=975
},
[13]={
index=868,
mountID=868
},
[14]={
index=947,
mountID=947
},
[15]={
index=780,
mountID=780
},
[16]={
index=981,
mountID=981
},
[17]={
index=883,
mountID=883
},
[18]={
index=1007,
mountID=1007
},
[19]={
index=960,
mountID=960
},
[20]={
index=800,
mountID=800
},
[21]={
index=930,
mountID=930
},
[22]={
index=1011,
mountID=1011
},
[23]={
index=972,
mountID=972
},
[24]={
index=826,
mountID=826
},
[25]={
index=932,
mountID=932
},
[26]={
index=763,
mountID=763
},
[27]=477,
[28]=1533,
[29]=1526,
[30]=1541,
<skipped 53>
}

Okay I don't know this Forum, but It seems weird that it put the first Line of the post above in this like "extra bar" on the top. Don't know how it is for you to read, so here is a screenshot of the first lines, the rest should be the same as in the post above

Thank you for sharing and sticking around.
I think I know what bug originally caused this. (#138) Although it shouldn't happen again, I didn't correct favorite profiles which already got affected.
I'm sorry that you had to deal with it this bug for so long. At least now I know what to do. 😄

No need to be sorry :-) You have an awesome addon. Keep up that good work : -)