Lua error thrown on mailbox item deletion

[Saaappi]

Please include as much of the following information as possible to help me fix the bug:

Brief Description of Bug

I tried to delete an item (a leftover letter) from a mailbox item.

Steps to Reproduce

It was either while Open All was running that I tried to delete the letter, or after Open All had completed and I tried to delete the letter.

It only failed once, and I was able to delete it the second time. Could have been a fluke. I hope the trace below helps you identify the issue.

Loaded Addons

• AddonFactory
• AllTheThings
• Baganator/Syndicator (obviously)
• BtWLoadouts
• BugGrabber/BugSack
• Delete Hearthstone
• Details!
• ExtraQuestButton
• Grail
• HelpMePlay
• MinimapButtonBag-Reborn
• OPie
• Plater
• TomTom
• Wholly
• WoWthing Collector
• Zygor

Back Trace (LUA Error Output)

1x Syndicator/Tracking/MailCache.lua:88: attempt to index local 'recipient' (a nil value)
[string "@Syndicator/Tracking/MailCache.lua"]:88: in function <Syndicator/Tracking/MailCache.lua:85>
[string "=[C]"]: in function `ReturnInboxItem'
[string "@Blizzard_MailFrame/MailFrame.lua"]:871: in function <Blizzard_MailFrame/MailFrame.lua:859>

Locals:
mailIndex = 3
recipient = nil
(*temporary) = 3
(*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = 0
(*temporary) = 0
(*temporary) = 0
(*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = "attempt to index local 'recipient' (a nil value)"
self = Frame {
 currentCharacter = "Artyfischel-AeriePeak"
}

[plusmouse]

Added a fix to prevent this error happening again.