crash on starting sudoku (makes it unusable)

[sleep-yearning]

Fresh install on Android 13 crashes the app as soon as play button is pressed and gives:
2023-05-31 12:19:06.253 17331-17331 yfriendlysudoku org.secuso.privacyfriendlysudoku E Invalid ID 0x00000000. 2023-05-31 12:19:06.287 17331-17331 AndroidRuntime org.secuso.privacyfriendlysudoku E FATAL EXCEPTION: main Process: org.secuso.privacyfriendlysudoku, PID: 17331 java.lang.RuntimeException: Unable to start activity ComponentInfo{org.secuso.privacyfriendlysudoku/org.secuso.privacyfriendlysudoku.ui.GameActivity}: java.lang.NullPointerException at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:4169) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:4325) at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:101) at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2574) at android.os.Handler.dispatchMessage(Handler.java:106) at android.os.Looper.loopOnce(Looper.java:226) at android.os.Looper.loop(Looper.java:313) at android.app.ActivityThread.main(ActivityThread.java:8757) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:571) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1067) Caused by: java.lang.NullPointerException at android.content.res.XmlBlock.nativeGetStyleAttribute(Native Method) at android.content.res.XmlBlock.-$$Nest$smnativeGetStyleAttribute(Unknown Source:0) at android.content.res.XmlBlock$Parser.getStyleAttribute(XmlBlock.java:471) at android.content.res.Resources$Theme.getExplicitStyle(Resources.java:1976) at android.view.View.retrieveExplicitStyle(View.java:6722) at android.view.View.<init>(View.java:5830) at android.view.View.<init>(View.java:5786) at android.view.View.<init>(View.java:5765) at org.secuso.privacyfriendlysudoku.ui.view.SudokuCellView.<init>(SudokuCellView.java:62) at org.secuso.privacyfriendlysudoku.ui.view.SudokuFieldLayout.setSettingsAndGame(SudokuFieldLayout.java:111) at org.secuso.privacyfriendlysudoku.ui.GameActivity.onCreate(GameActivity.java:328) at android.app.Activity.performCreate(Activity.java:8591) at android.app.Activity.performCreate(Activity.java:8570) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1384) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:4150) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:4325)  at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:101)  at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)  at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2574)  at android.os.Handler.dispatchMessage(Handler.java:106)  at android.os.Looper.loopOnce(Looper.java:226)  at android.os.Looper.loop(Looper.java:313)  at android.app.ActivityThread.main(ActivityThread.java:8757)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:571)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1067)