Reports a warning from the parser. Warning messages are generated by the parser when it encounters data that is
syntactically correct but which is likely to be a typo. Examples are the use of unknown or deprecated RDF URIs,
e.g. rdfs:Property instead of rdf:Property.
Reports an error from the parser. Error messages are generated by the parser when it encounters an error in the
RDF document. The parser will try its best to recover from the error and continue parsing when
stopAtFirstError has been set to false.
Reports a fatal error from the parser. A fatal error is an error of which the RDF parser cannot recover. The
parser will stop parsing directly after it reported the fatal error. Example fatal errors are unbalanced start-
and end-tags in an XML-encoded RDF document.