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.