Description:
This is happening somewhat often for me now. When I go to close np++, it throws up the error dialog and points me to the error log. The entries look like this:

============================================================
WHAT : Error when saving settings : Collection was modified; enumeration operation may not execute.
WHEN : 2/2/2019 1:32:03 PM
WHERE : System.ThrowHelper.ThrowInvalidOperationException(), line 0
DETAILS :
System.InvalidOperationException: Collection was modified; enumeration operation may not execute.
at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
at System.Collections.Generic.Dictionary2.KeyCollection.Enumerator.MoveNext() at _3PA.Lib.Object2Xml1.DictToXml(Dictionary2 inputDict, String elmName, String subElmName, Boolean valueInAttribute) in c:\projects\3p\3PA\Lib\Object2Xml.cs:line 246 at _3PA.Lib.Object2Xml1.SaveToXElement(T item, Boolean valueInAttribute) in c:\projects\3p\3PA\Lib\Object2Xml.cs:line 105
at _3PA.Lib.Object2Xml1.SaveToXDocument(List1 instance, Boolean valueInAttribute) in c:\projects\3p\3PA\Lib\Object2Xml.cs:line 82
at _3PA.Lib.Object2Xml1.SaveToFile(List1 instance, String filename, Boolean valueInAttribute) in c:\projects\3p\3PA\Lib\Object2Xml.cs:line 67
at _3PA.Lib.Object2Xml`1.SaveToFile(T instance, String filename, Boolean valueInAttribute) in c:\projects\3p\3PA\Lib\Object2Xml.cs:line 56
at _3PA.MainFeatures.Config.Save() in c:\projects\3p\3PA\MainFeatures\Config.cs:line 856

Steps to Reproduce the Issue

open a bunch of files
close npp

Expected Behavior

clean shutdown

Actual Behavior

error dialog

Screenshots

nothing special

Debug Information

Notepad++ v7.5.9 (32-bit)
Build time : Oct 14 2018 - 15:02:52
Path : C:\Program Files (x86)\Notepad++\notepad++.exe
Admin mode : ON
Local Conf mode : OFF
OS : Windows 10 (64-bit)
Plugins : DSpellCheck.dll mimeTools.dll NppConverter.dll NppExport.dll 3P.dll ComparePlugin.dll HTMLTag_unicode.dll JSMinNPP.dll NppColumnSort.dll NPPJSONViewer-win32.dll PluginManager.dll SpellChecker.dll VisualStudioLineCopy.Unicode.dll XBrackets.dll XMLTools.dll