endless vendor cycle

Bot can't rebuy food and grind  at same preferences.

If i tuning on buying food (in plugin, anti afk and humanizing) then bot buying food then go mail, then go vendor, then go mail, then go mail and so on.

if i turning off buying food then bot not buying food at all but grinding good.

if i turning off plugin then bot not buying food at all but grinding good.

00:06:03 - [Grinder] Started
[D] 00:06:03 - [Spell] Sinister Strike (Id found: 26862, Name found: Sinister Strike, NameInGame found: Sinister Strike, Know = True, IsSpellUsable = True)
00:06:03 - [MoveDuringCombat] Loadded.
00:06:03 - [MasterPlugin] Started.
00:06:08 - [ToTown] Go to vendor Caregiver Isel (Vendor)
[F] 00:06:23 - [Spell] Cast Stealth (Stealth)
[F] 00:06:23 - [Spell] Cast Stealth (Stealth)
[F] 00:06:24 - [Spell] Cast Stealth (Stealth)
00:06:24 - [ToTown] Vendor found Caregiver Isel
00:06:24 - [ToTown] Sell items (try 1)
[E] 00:06:24 - SellItems(List<String> itemSell, List<string> itemNoSell, List<Enums.WoWItemQuality> itemQuality): System.InvalidOperationException: Коллекция была изменена; невозможно выполнить операцию перечисления.
   в System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
   в System.Collections.Generic.List1.Enumerator.MoveNextRare()
   в System.Collections.Generic.List1.Enumerator.MoveNext()
   в System.Linq.Enumerable.Aggregate[TSource,TAccumulate](IEnumerable1 source, TAccumulate seed, Func3 func)
   в wManager.Wow.Helpers.Vendor.SellItems(List1 itemSell, List1 itemNoSell, List`1 itemQuality)

00:06:27 - [ToTown] Buy drink and food
00:06:27 - [ToTown] Go to MailBox (Mailbox - Mailbox)
[D] 00:06:27 - [MovementManager]  You try to use flying/swimming path but you cannot fly/swim here, try to use ground mouvement...
[D] 00:06:38 - [MovementManager]  You try to use flying/swimming path but you cannot fly/swim here, try to use ground mouvement...
00:06:39 - [ToTown] MailBox found
00:06:42 - [ToTown] Mail sending at I...
00:06:43 - [Mount] Mounting ground mount Swift Brown Steed