android.view.WindowManager$BadTokenException: Unable to add window -- token null is not valid; is your activity running? in react-native android I want to show a custom view when the app is turned off or when the app is turned on, depending on the phone state. so I use WindowManager. but get error message W/System.err: android.view.WindowManager$BadTokenException: Unable to add window -- token null is not valid; is your activity running? W/System.err: at android.view.ViewRootImpl.setView(ViewRootImpl.java:1596) W/System.err: at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:509) W/System.err: at...