I have defined a simple custom View by extending LinearLayout. The crux is that it contains an ExpandableListView with a header view added:

public class MyView extends LinearLayout {
private View mHeaderView;
private ExpandableListView mListView;

@SuppressWarnings("UnusedDeclaration")
public MyView(Context context) {
    super(context);
    init(context);
}

@SuppressWarnings("UnusedDeclaration")
public MyView(Context context, AttributeSet attrs) {
    super(context, attrs);
    init(context);
}

private void init(Context context) {
    setOrientation(LinearLayout.VERTICAL);
    setDescendantFocusability(ViewGroup.FOCUS_AFTER_DESCENDANTS);
    LayoutInflater inflater = LayoutInflater.from(context);

    //Inflate custom view into LinearLayout
    inflater.inflate(
            R.layout.merge_myview, this);

    //Inflate header with no parent so we can set it as the ListView header in onFinishInflate()
    mHeaderView = inflater.inflate(R.layout.header_bundles_list, null);
}

@Override
protected void onFinishInflate() {
    super.onFinishInflate();

    mListView = (ExpandableListView) (findViewById(R.id.lv_expandable));

    Log.d("MyView", "Almost done...");

    //Commenting out this line makes it work
    mListView.addHeaderView(mHeaderView, null, false);
}
}

Here's merge_myview.xml:

<merge xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ExpandableListView
        android:id="@+id/lv_expandable"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />    
</merge>

Here's the header:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
     >

    <TextView
        android:id="@+id/tv_title"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:background="#EFEEFF"
        android:clickable="true"
        android:gravity="center"
        android:minHeight="96dp"
        android:onClick="openPane"
        android:paddingBottom="24dp"
        android:paddingTop="24dp"
        android:text="HELLO!"
        android:textColor="#333333"
        android:textIsSelectable="true"
        android:textSize="48sp" />

</RelativeLayout>

With a plain onCreate in my activity:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_myview);
}

Where activity_myview.xml contains only my custom view:

<com.example.app.MyView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:orientation="vertical"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"/>

However, when I run this app, I get the following error:

java.lang.NullPointerException   at
 android.widget.ListView.clearRecycledState(ListView.java:507)   at
 android.widget.ListView.resetList(ListView.java:493)   at
 android.widget.ListView.layoutChildren(ListView.java:1431)   at
 android.widget.AbsListView.onLayout(AbsListView.java:1147)   at
 android.view.View.layout(View.java:7035)   at
 android.widget.LinearLayout.setChildFrame(LinearLayout.java:1252)   at
 android.widget.LinearLayout.layoutVertical(LinearLayout.java:1128)   at
 android.widget.LinearLayout.onLayout(LinearLayout.java:1045)   at
 android.view.View.layout(View.java:7035)   at
 android.widget.FrameLayout.onLayout(FrameLayout.java:333)   at
 android.view.View.layout(View.java:7035)   at
 android.widget.LinearLayout.setChildFrame(LinearLayout.java:1252)   at
 android.widget.LinearLayout.layoutVertical(LinearLayout.java:1128)   at 
 android.widget.LinearLayout.onLayout(LinearLayout.java:1045)   at
 android.view.View.layout(View.java:7035)   at
 android.widget.LinearLayout.setChildFrame(LinearLayout.java:1252)   at
 android.widget.LinearLayout.layoutVertical(LinearLayout.java:1128)   at
 android.widget.LinearLayout.onLayout(LinearLayout.java:1045)   at
 android.view.View.layout(View.java:7035)

I suppose this is a bug that was fixed somewhere between Android 2.3.7 and 4.1.1, because I only get the error when testing with the former. I can't find it in the bug tracker, though. So why does this error occur? And is there any workaround?

EDIT

I think this is the bug, fixed in June 2013.