Bug: deletion of all characters using long pressing the backspace button crashes

[AndroidDeveloperLB]

Crash log:

02-12 17:52:14.462 29538-29538/com.onegravity.rteditor.demo E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.onegravity.rteditor.demo, PID: 29538
    java.util.ConcurrentModificationException
        at java.util.ArrayList$Itr.next(ArrayList.java:860)
        at com.onegravity.rteditor.effects.ParagraphSpanProcessor.process(ParagraphSpanProcessor.java:70)
        at com.onegravity.rteditor.effects.BulletEffect.applyToSelection(BulletEffect.java:75)
        at com.onegravity.rteditor.effects.BulletEffect.applyToSelection(BulletEffect.java:39)
        at com.onegravity.rteditor.effects.Effects.cleanupParagraphs(Effects.java:128)
        at com.onegravity.rteditor.effects.Effects.cleanupParagraphs(Effects.java:117)
        at com.onegravity.rteditor.RTEditText.onSelectionChanged(RTEditText.java:633)
        at android.widget.TextView.spanChange(TextView.java:9510)
        at android.widget.TextView$ChangeWatcher.onSpanChanged(TextView.java:11951)
        at android.text.SpannableStringBuilder.sendSpanChanged(SpannableStringBuilder.java:1292)
        at android.text.SpannableStringBuilder.sendToSpanWatchers(SpannableStringBuilder.java:647)
        at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:577)
        at android.text.SpannableStringBuilder.delete(SpannableStringBuilder.java:229)
        at android.text.SpannableStringBuilder.delete(SpannableStringBuilder.java:227)
        at android.text.method.BaseKeyListener.backspaceOrForwardDelete(BaseKeyListener.java:370)
        at android.text.method.BaseKeyListener.backspace(BaseKeyListener.java:71)
        at android.text.method.BaseKeyListener.onKeyDown(BaseKeyListener.java:479)
        at android.text.method.QwertyKeyListener.onKeyDown(QwertyKeyListener.java:362)
        at android.text.method.TextKeyListener.onKeyDown(TextKeyListener.java:141)
        at android.widget.TextView.doKeyDown(TextView.java:7318)
        at android.widget.TextView.onKeyDown(TextView.java:7095)
        at android.view.KeyEvent.dispatch(KeyEvent.java:2691)
        at android.view.View.dispatchKeyEvent(View.java:11713)
        at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1834)
        at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1834)
        at android.widget.ScrollView.dispatchKeyEvent(ScrollView.java:389)
        at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1834)
        at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1834)
        at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1834)
        at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1834)
        at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1834)
        at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1834)
        at com.android.internal.policy.DecorView.superDispatchKeyEvent(DecorView.java:440)
        at com.android.internal.policy.PhoneWindow.superDispatchKeyEvent(PhoneWindow.java:1819)
        at android.app.Activity.dispatchKeyEvent(Activity.java:3267)
        at android.support.v7.app.AppCompatActivity.dispatchKeyEvent(AppCompatActivity.java:534)
        at android.support.v7.view.WindowCallbackWrapper.dispatchKeyEvent(WindowCallbackWrapper.java:58)
        at android.support.v7.app.AppCompatDelegateImplBase$AppCompatWindowCallbackBase.dispatchKeyEvent(AppCompatDelegateImplBase.java:316)
        at com.android.internal.policy.DecorView.dispatchKeyEvent(DecorView.java:354)
        at android.view.ViewRootImpl$ViewPostImeInputStage.processKeyEvent(ViewRootImpl.java:4733)
        at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:4605)
        at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4147)
        at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4200)
        at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4166)
        at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:4293)
        at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4174)
        at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:4350)
        at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4147)
        at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4200)
        at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4166)
        at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4174)
        at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4147)
        at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:6661)
        at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:6635)
        at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:6596)
        at android.view.ViewRootImpl$ViewRootHandler.handleMessage(ViewRootImpl.java:3930)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:164)
        at android.app.ActivityThread.main(ActivityThread.java:6494)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
02-12 17:52:15.311 16035-16080/? E/ctxmgr: [WorkInfo]Attribution was already enqueued pkg=com.google.android.gms, lbl=PlacesProducer_receive, start=unspec, stop=unspec.
02-12 17:52:15.317 16035-29717/? E/ctxmgr: [WorkManager]Ongoing task not found: PlacesProducer_receive
02-12 17:52:15.808 16035-16035/? E/ctxmgr: [PlaceFenceHelper]NearbyBuffer is null!
02-12 17:53:02.291 1625-1625/? E/QtiImsExtUtils: getConfigForPhoneId phoneId is invalid
    isCarrierConfigEnabled bundle is null
02-12 17:53:19.693 30465-30486/? E/native: jni_helper.cc:170 GetContents failed: /data/user/0/com.google.android.gms/app_vision/ocr/data/models/semanticlift_engine_0.2.bincfg