v4.0 crash report - NPE at UploadMediaDetailFragment.java:155

[misaochan]

From google groups forum:

USER_COMMENT=I switched apps, then switched back again, and this error popped up
APP_VERSION_CODE=1027
APP_VERSION_NAME=4.0.1
ANDROID_VERSION=11
PHONE_MODEL=moto g(9) plus
STACK_TRACE=java.lang.NullPointerException: Attempt to invoke interface method 'int fr.free.nrw.commons.upload.mediaDetails.UploadMediaDetailFragment$UploadMediaDetailFragmentCallback.getIndexInViewFlipper(fr.free.nrw.commons.upload.UploadBaseFragment)' on a null object reference
at fr.free.nrw.commons.upload.mediaDetails.UploadMediaDetailFragment.init(UploadMediaDetailFragment.java:155)
at fr.free.nrw.commons.upload.mediaDetails.UploadMediaDetailFragment.onViewCreated(UploadMediaDetailFragment.java:151)
at androidx.fragment.app.FragmentStateManager.createView(FragmentStateManager.java:322)
at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1185)
at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1354)
at androidx.fragment.app.FragmentManager.moveFragmentToExpectedState(FragmentManager.java:1432)
at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1495)
at androidx.fragment.app.FragmentManager.dispatchStateChange(FragmentManager.java:2617)
at androidx.fragment.app.FragmentManager.dispatchActivityCreated(FragmentManager.java:2569)
at androidx.fragment.app.FragmentController.dispatchActivityCreated(FragmentController.java:247)
at androidx.fragment.app.FragmentActivity.onStart(FragmentActivity.java:541)
at androidx.appcompat.app.AppCompatActivity.onStart(AppCompatActivity.java:201)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1435)
at android.app.Activity.performStart(Activity.java:8134)
at android.app.ActivityThread.handleStartActivity(ActivityThread.java:3534)
at android.app.servertransaction.TransactionExecutor.performLifecycleSequence(TransactionExecutor.java:221)
at android.app.servertransaction.TransactionExecutor.cycleToPath(TransactionExecutor.java:201)
at android.app.servertransaction.TransactionExecutor.executeLifecycleState(TransactionExecutor.java:173)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:97)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2132)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:250)
at android.app.ActivityThread.main(ActivityThread.java:7848)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:958)