Cannot access runtime errors

[jakiestfu]

When applying a document to a stylesheet, there are runtime errors reported in the console but it is not reflected in any error object.

runtime error: element value-of
Variable 'foobar' has not been declared.
xmlXPathCompiledEval: evaluation failed
runtime error: element value-of
XPath evaluation returned no result.

[albanm]

It seems that the original libxslt library doesn't consider these errors as a real failure, a document is still produced as a result of the transformation. So it is more warnings than errors.

I don't know if there is an option to force failure on this kind of error.

[rainabba]

Any way to expose those in the results of apply(), even if not qualified as errors?