Missing semantic validation of DMN file

If a semantically wrong file is parsed by the marshaller, exception may be thrown but they are not meaningfull.
As example, the attached file raise a NPE at DMNMarshallerStandalone because at this line

Node sourceNode = Optional.ofNullable(elems.get(sourceId)).map(Entry::getValue).orElse(textAnnotations.get(sourceId));

elements is empty.

So, even if the file is syntactically correct, it is semantically wrong; but this semantic check seems not implemented.

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