Results parsers must work without handlers

The follow throws a NPE. However, a QueryResultParseException is expected.

ByteArrayOutputStream out = new ByteArrayOutputStream();
TupleQueryResult tqr = new TupleQueryResultImpl(Arrays.asList("x"), Collections.<BindingSet>emptyList());
QueryResultIO.write(tqr, TupleQueryResultFormat.SPARQL, out);

ByteArrayInputStream in = new ByteArrayInputStream(out.toByteArray());
QueryResultIO.createParser(getBooleanFormat()).parse(in);