This error is from another implementation, though there are minimal changes to this - so likely could also be an issue with the core version.
Full stack trace:
05-09 11:53:39.000 6210-6210/com.vtrmob.admin E/WindowManager: android.view.WindowLeaked: Activity org.digitalcampus.oppia.activity.WelcomeActivity has leaked window com.android.internal.policy.PhoneWindow$DecorView{e927a0d V.E...... R......D 0,0-684,322} that was originally added here
at android.view.ViewRootImpl.(ViewRootImpl.java:368)
at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:299)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:85)
at android.app.Dialog.show(Dialog.java:319)
at org.digitalcampus.oppia.fragments.LoginFragment.onLoginClick(LoginFragment.java:104)
at org.digitalcampus.oppia.fragments.LoginFragment$1.onClick(LoginFragment.java:84)
at android.view.View.performClick(View.java:5198)
at android.view.View$PerformClick.run(View.java:21147)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
05-09 11:53:39.005 6210-6317/com.vtrmob.admin E/Surface: getSlotFromBufferLocked: unknown buffer: 0xaecb3ed0
05-09 11:53:39.010 6210-6210/com.vtrmob.admin I/Choreographer: Skipped 98 frames! The application may be doing too much work on its main thread.
05-09 11:53:39.539 1182-1820/? E/BufferQueueProducer: [Login] queueBuffer: BufferQueue has been abandoned
05-09 11:53:39.539 6210-6210/com.vtrmob.admin E/Surface: queueBuffer: error queuing buffer to SurfaceTexture, -19
05-09 11:53:39.539 6210-6210/com.vtrmob.admin E/Surface: queueBuffer (handle=0xa1ed4d20) failed (No such device)
05-09 11:53:39.540 6210-6210/com.vtrmob.admin E/ViewRootImpl: Could not unlock surface
java.lang.IllegalArgumentException
at android.view.Surface.nativeUnlockCanvasAndPost(Native Method)
at android.view.Surface.unlockSwCanvasAndPost(Surface.java:301)
at android.view.Surface.unlockCanvasAndPost(Surface.java:282)
at android.view.ViewRootImpl.drawSoftware(ViewRootImpl.java:2739)
at android.view.ViewRootImpl.draw(ViewRootImpl.java:2642)
at android.view.ViewRootImpl.performDraw(ViewRootImpl.java:2434)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2067)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1107)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6013)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:858)
at android.view.Choreographer.doCallbacks(Choreographer.java:670)
at android.view.Choreographer.doFrame(Choreographer.java:606)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:844)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)