QXmlStreamWriter::writeCharacters() doesn't properly escape control characters, causing QXmlStreamReader::readNext() to raise an error

Using writeCharacters() should yield output that is parseable by QXmlStreamReader.
But if the source string contains, for example, the ESC character (0x1B), that won't get escaped, and as a result, the reader will raise an error.
Either writeCharacters() should escape those characters, or QXmlStreamReader must accept them in the input stream.