Sometimes exception occurs when gaining focus

• What happened?
  Error pops up:

In update thread: [string "#@..."]: 47: attempt to index local 'outFile' (a nil value)
stack traceback:
[string "#@..."]: 47: in function 'downloadFile'
[string "#@..."]: 175: in main chunk
Press Enter/Escape to Dismiss, or F5 to restart the application.

Problem will persist upon either dismissing or restarting the application.

• What were you trying to do?
  Switching to POB from POE.

• What steps will reproduce the bug?
  When POB is minimized on a second monitor and I ALT-TAB into it.

• Does it reproduce every time?
  Problem does not reproduce 100% of the time but is rather frequent.

• Provide a build code:
  Running 1.4.170.24 on Windows 10.

• Screenshots:
  https://imgur.com/a/VhkhIYr

2台目のモニターで POB を最小化し、Windows 10 で Alt-Tab を使用してフォーカス変更を再現します。報告されたスタックトレースの位置にある update-thread の downloadFile 関数から調査を開始し、なぜ outFile が nil なのかを調べます。フォーカスを切り替えても例外が発生せず、閉じるか再起動した後もアプリケーションを引き続き使用できれば完了です。