#vulnerable code 
                                public <T, S extends Geometry> RTree<T, S> deserialize(long sizeBytes, InputStream is,
            Func1<byte[], T> deserializer) throws IOException {
        byte[] bytes = readFully(is, (int) sizeBytes);
        Tree_ t = Tree_.getRootAsTree_(ByteBuffer.wrap(bytes));
        Node_ node = t.root();
        Context<T, S> context = new Context<T, S>(t.context().minChildren(),
                t.context().maxChildren(), new SelectorRStar(), new SplitterRStar(),
                new FactoryImmutable<T, S>());
        Node<T, S> root = new NonLeafFlatBuffersStatic<T, S>(node, context, deserializer);
        return SerializerHelper.create(Optional.of(root), 1, context);
    } 
                            #location 9 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                public <T, S extends Geometry> RTree<T, S> deserialize(long sizeBytes, InputStream is,
            Func1<byte[], T> deserializer) throws IOException {
        byte[] bytes = readFully(is, (int) sizeBytes);
        Tree_ t = Tree_.getRootAsTree_(ByteBuffer.wrap(bytes));
        Node_ node = t.root();
        Context<T, S> context = new Context<T, S>(t.context().minChildren(),
                t.context().maxChildren(), new SelectorRStar(), new SplitterRStar(),
                new FactoryImmutable<T, S>());
        final Node<T, S> root;
        if (node.childrenLength() > 0)
            root = new NonLeafFlatBuffersStatic<T, S>(node, context, deserializer);
        else {
            List<Entry<T, S>> entries = FlatBuffersHelper.createEntries(node, deserializer);
            root = new LeafDefault<T, S>(entries, context);
        }
        return SerializerHelper.create(Optional.of(root), (int) t.size(), context);
    }