Prevent IllegalArgumentException when closing popup

[Stypox]

What is it?

• Bugfix (user facing)
• Feature (user facing)
• Codebase improvement (dev facing)
• Meta improvement to the project (dev facing)

Description of the changes in your PR

This PR fixes a random crash when closing the popup player. I could reproduce it consistently on dev by closing the popup player via the X in the notification, but it also happens on 0.20.8 at random times.

Fixes

Crash log

java.lang.RuntimeException: Unable to stop service org.schabi.newpipe.player.MainPlayer@56760fc: java.lang.IllegalArgumentException: View=android.widget.FrameLayout{759337c V.E...... ........ 0,0-1080,1965} not attached to window manager
	at android.app.ActivityThread.handleStopService(ActivityThread.java:4136)
	at android.app.ActivityThread.access$1900(ActivityThread.java:219)
	at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1896)
	at android.os.Handler.dispatchMessage(Handler.java:107)
	at android.os.Looper.loop(Looper.java:214)
	at android.app.ActivityThread.main(ActivityThread.java:7356)
	at java.lang.reflect.Method.invoke(Native Method)
	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:491)
	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:940)
Caused by: java.lang.IllegalArgumentException: View=android.widget.FrameLayout{759337c V.E...... ........ 0,0-1080,1965} not attached to window manager
	at android.view.WindowManagerGlobal.findViewLocked(WindowManagerGlobal.java:517)
	at android.view.WindowManagerGlobal.removeView(WindowManagerGlobal.java:426)
	at android.view.WindowManagerImpl.removeView(WindowManagerImpl.java:121)
	at org.schabi.newpipe.player.Player.removePopupFromView(Player.java:1358)
	at org.schabi.newpipe.player.MainPlayer.onDestroy(MainPlayer.java:192)
	at android.app.ActivityThread.handleStopService(ActivityThread.java:4116)
	... 8 more

Due diligence

• I read the contribution guidelines.

[Redirion]

more a symptomatic fix, but trivial enough to directly merge it. Is also hard to debug.

[Stypox]

@XiangRongLin feel free to merge ;-)