Inconsistency: Invalid view holder adapter when using FirestorePagingAdapter with custom wrapper

Question

I wrote a wrapper around FirestorePagingAdapter. This works fine most of the times. But there are occasions where this crashes with

java.lang.IndexOutOfBoundsException: Inconsistency detected. Invalid view holder adapter

I will show you the complete wrapper. Also the last log message I see before the crash is

[Paging adapter] Data loading finished.

I also noticed, when I slowly scroll the list it works fine. Only if I scroll the list fast it crashes eventually.

So here is the code. I cannot figure out where the problem is. Any help is highly appreciated

public abstract class PagingAdapter<T extends RecyclerItem> extends FirestorePagingAdapter<T, RecyclerViewHolder<T, ? extends ViewBinding>> implements Function1<CombinedLoadStates, Unit> {
protected final String TAG = this.getClass().getSimpleName();
private final SnapshotParser<T> mParser;
private SortedList<T> mListItems;

private int mTryCount;
private boolean mReverseFill = false;


private PagingAdapter(@NonNull FirestorePagingOptions<T> options, PagingAdapterCallback<T> callback) {
    super(options);

        mListItems = new SortedList(RecyclerItem.class, new SortedListAdapterCallback<T>(this) {
            @Override
            public int compare(T o1, T o2) {
                return callback.compare(o1, o2);
            }

            @Override
            public boolean areContentsTheSame(T oldItem, T newItem) {
                return callback.areContentsTheSame(oldItem, newItem);
            }

            @Override
            public boolean areItemsTheSame(T item1, T item2) {
                return callback.areContentsTheSame(item1, item2);
            }
        });

    mParser = options.getParser();
    this.mTryCount = 0;
}

public void setReverseFill(boolean reverseFill) {
    this.mReverseFill = reverseFill;
}

@Override
public int getItemViewType(int position) {
    return getList().get(position).getRecyclerItemType().getId();
}

public SortedList<T> getList() {
    return mListItems;
}


@NonNull
@Override
public RecyclerViewHolder<T, ? extends ViewBinding> onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    RecyclerViewHolder<T, ? extends ViewBinding> viewHolder = onCreateViewHolder(parent, RecyclerItemType
            .get(viewType));
    if (viewHolder == null) {
        throw new NullPointerException("Your list contains items for that you did not specify a view holder for");
    }
    return viewHolder;
}

public abstract RecyclerViewHolder<T, ? extends ViewBinding> onCreateViewHolder(@NonNull ViewGroup parent, RecyclerItemType itemType);

@Override
public void onBindViewHolder(RecyclerViewHolder<T, ? extends ViewBinding> holder, int position) {
    try {
        //and trigger the paging to load around with the correct "position"
        super.onBindViewHolder(holder, getPagingPosition(position)); //<--Needed to page the list, be we do not really use it (see below)
    } catch (Exception ignore) {
        //If this fails, because there are less items in the list, do not crash, this is fine
        Log.d(TAG, "onBindViewHolder: ");
    }
    holder.bind(getList().get(position));
}

protected int getPagingPosition(int requestedPosition) {
    return requestedPosition;
}

@Override
protected void onBindViewHolder(@NonNull RecyclerViewHolder<T, ? extends ViewBinding> holder, int position, @NonNull T model) {
    //We do not use this method
}

@Override
public int getItemCount() {
    return getList().size();
}

@Override
public Unit invoke(CombinedLoadStates states) {
    LoadState refresh = states.getRefresh();
    LoadState append = states.getAppend();

    if (refresh instanceof LoadState.Error || append instanceof LoadState.Error) {
        //The previous load (either initial or additional) failed
        Log.d(TAG, "[Paging adapter] An error occurred while loading the data");
        if (mTryCount < 3) {
            mTryCount += 1;
            retry();
        } 
    }

    if (refresh instanceof LoadState.Loading) {
        Log.d(TAG, "[Paging adapter] Loading initial data");
    }

    if (append instanceof LoadState.Loading) {
        Log.d(TAG, "[Paging adapter] Loading more data");   
    }

    if (append instanceof LoadState.NotLoading) {
        LoadState.NotLoading notLoading = (LoadState.NotLoading) append;
        if (notLoading.getEndOfPaginationReached()) {
            Log.d(TAG, "[Paging adapter] No further documents");
            mTryCount = 0;
            return null;
        }

        if (refresh instanceof LoadState.NotLoading) {
            Log.d(TAG, "[Paging adapter] Data loading finished");
            mTryCount = 0;
            List<T> items = new ArrayList<>();
            if (mReverseFill) {
                for (int i = snapshot().size() - 1; i >= 0; i--) {
                    T currentItem = mParser.parseSnapshot(snapshot().get(i));
                    if (getList().indexOf(currentItem) == SortedList.INVALID_POSITION)
                        items.add(currentItem);
                }
            } else {
                for (DocumentSnapshot snapshot : snapshot()) {
                    T currentItem = mParser.parseSnapshot(snapshot);
                    if (getList().indexOf(currentItem) == SortedList.INVALID_POSITION)
                        items.add(currentItem);
                }
            }
            addAll(items);
            return null;
        }
    }
    return null;
}

public void addAll(Collection<T> items) {
    getList().beginBatchedUpdates();
    getList().addAll(items);
    getList().endBatchedUpdates();
}


public abstract static class PagingAdapterCallback<T extends RecyclerItem> {
    public abstract int compare(T o1, T o2);

    public abstract boolean areContentsTheSame(T oldItem, T newItem);

    public abstract boolean areItemsTheSame(T item1, T item2);
}
}

Just in case you wonder. These are the other two wrapper:

public abstract class RecyclerViewHolder<T extends RecyclerItem, E extends ViewBinding> extends RecyclerView.ViewHolder {
public final String TAG = this.getClass().getSimpleName();
protected final E b;
private final Context mContext;

protected RecyclerViewHolder(@NonNull E b) {
    super(b.getRoot());
    this.b = b;
    this.mContext = b.getRoot().getContext();
}

public abstract void bind(T item);

protected Context getContext() {
    return mContext;
}

protected Context requireContext() {
    return getContext();
}

protected String getString(int resId) {
    return mContext.getString(resId);
}

protected String getString(int resId, Object... args) {
    return mContext.getString(resId, args);
}

}

and

public interface RecyclerItem {

 @NonNull
 RecyclerItemType getRecyclerItemType();

 default void setRecyclerItemType(RecyclerItemType type){
      //Does not do anything per default
 }

}