com.sun.org.apache.xml.internal.serialize.DOMSerializerImpl.writeToString(Node) has code like this:

try {
  // ...
} catch (RuntimeException e) {
  // ...
  throw new LSException(LSException.SERIALIZE_ERR, e.toString());
} catch (IOException ioe) {
  // ...
  throw new DOMException(DOMException.DOMSTRING_SIZE_ERR, msg);
}

If there is a failure from some implementation-internal code, the stack trace will be lost.

Observed because prepareForSerialization can throw NPE in

  next = node.getNextSibling();

which I will report separately if I can figure out under which conditions it occurs.

Observed in JDK 5 but JDK 7 seems to still have the same code.