fix stack

android/app/src/main/java/com/reactnativenavigation/layouts/ScreenImpl.java

@@ -5,7 +5,6 @@ import android.app.Activity;
 import android.content.Context;
 import android.graphics.Color;
 import android.os.Build;
-import android.util.Log;
 import android.view.View;
 import android.view.Window;
 import android.widget.RelativeLayout;
@@ -108,7 +107,6 @@ public class ScreenImpl extends RelativeLayout implements Screen, ScrollDirectio
 
     @Override
     public void onScrollChanged(ScrollDirectionListener.Direction direction) {
-        Log.d("TAG", "onScrollChanged: ");
         if (scrollAnimator == null) {
             scrollAnimator = new OnScrollAnimator(topBar, OnScrollAnimator.HideDirection.Up, topBar.getHeight());
         }

android/app/src/main/java/com/reactnativenavigation/layouts/ScreenStack.java

@@ -21,9 +21,13 @@ public class ScreenStack extends FrameLayout {
     }
 
     public void push(ScreenParams screenParams) {
-        Screen previous = stack.peek();
-        addScreen(screenParams);
-        removePreviousWithoutUnmount(previous);
+        if (isEmpty()) {
+            addScreen(screenParams);
+        } else {
+            Screen previous = stack.peek();
+            addScreen(screenParams);
+            removePreviousWithoutUnmount(previous);
+        }
     }
 
     private void addScreen(ScreenParams screenParams) {