Program Crashes on Startup with System.InvalidOperationException

[scottbright22]

Program is getting System.InvalidOperationException on my Kindle Scribe.
It seems like it's a threading problem and might need a semaphore.
Changing the timer to 10 seconds gets around the issue.

This Code Gets it to Work Again:

    private void CheckKindle()
    {
        CheckKindleType(); //New
        Timer aTimer = new(10000); //Changed
        aTimer.Elapsed += OnTimedEvent!;
        aTimer.AutoReset = true;
        aTimer.Enabled = true;
    }

System.InvalidOperationException
HResult=0x80131509
Message=Collection was modified; enumeration operation may not execute.
Source=System.Private.CoreLib
StackTrace:
at System.ThrowHelper.ThrowInvalidOperationException_InvalidOperation_EnumFailedVersion()
at System.Collections.Generic.List`1.Enumerator.MoveNext()
at Kindle_Cover_Fixer_V2.MainWindow.IsOnKindleScribe() in D:\VS_Source\kindle-cover-fixer-main\Kindle Cover Fixer V2\LibraryCheckKindle.cs:line 60
at Kindle_Cover_Fixer_V2.MainWindow.IsOnKindlePreparation() in D:\VS_Source\kindle-cover-fixer-main\Kindle Cover Fixer V2\LibraryCheckKindle.cs:line 41
at Kindle_Cover_Fixer_V2.MainWindow.FindBooksTask() in D:\VS_Source\kindle-cover-fixer-main\Kindle Cover Fixer V2\FindBooks.cs:line 17
at System.Threading.Thread.StartHelper.Callback(Object state)
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)