Q:

Stanford Core NLP example code SemanticGraph exception

I have just tried out the Core NLP example code, included as StanfordCoreNlpDemo.java with the download.  When trying to parse a chapter of a book, an exception is thrown from the Semantic Graph:
Exception in thread "main" java.lang. NullPointerException
at edu.stanford.nlp.semgraph. SemanticGraph.removeEdge(SemanticGraph.java:122)
at edu.stanford.nlp.trees. UniversalEnglishGrammaticalStructure.expandPPConjunction(UniversalEnglishGrammaticalStructure.java:553)
at edu.stanford.nlp.trees. UniversalEnglishGrammaticalStructure.expandPPConjunctions(UniversalEnglishGrammaticalStructure.java:508)
at edu.stanford.nlp.trees. UniversalEnglishGrammaticalStructure.collapseDependencies(UniversalEnglishGrammaticalStructure.java:807)
at edu.stanford.nlp.trees. GrammaticalStructure.typedDependenciesCollapsed(GrammaticalStructure.java:877)
at edu.stanford.nlp.semgraph. SemanticGraphFactory.makeFromTree(SemanticGraphFactory.java:188)
at edu.stanford.nlp.semgraph. SemanticGraphFactory.generateCollapsedDependencies(SemanticGraphFactory.java:90)
at edu.stanford.nlp.pipeline. ParserAnnotatorUtils.fillInParseAnnotations(ParserAnnotatorUtils.java:51)
at edu.stanford.nlp.pipeline. ParserAnnotator.finishSentence(ParserAnnotator.java:266)
at edu.stanford.nlp.pipeline. ParserAnnotator.doOneSentence(ParserAnnotator.java:245)
at edu.stanford.nlp.pipeline. SentenceAnnotator.annotate(SentenceAnnotator.java:96)
at edu.stanford.nlp.pipeline. AnnotationPipeline.annotate(AnnotationPipeline.java:68)
at edu.stanford.nlp.pipeline. StanfordCoreNLP.annotate(StanfordCoreNLP.java:412)
at epubReader. Test.main(Test.java:68)

I have narrowed it down to one sentence being responsible, even when parsed alone:
"Generally speaking, he was a scout, and rarely stood at a watch nearer than the four hundred and fiftieth metre, and then only as a cordon commander." 

Is there anything special about the syntax or semantics of the sentence that I am missing, causing the error? 

A:

No, the sentence is fine and this is unfortunately a bug in our dependency converter.  
The part-of-speech tagger outputs a really weird POS sequence causing the parser to produce a completely wrong parse tree which leads to this exception in the constituency-to-dependency converter.  
I fixed the bug in the converter but unless you clone the code from GitHub and compile it yourself, this won't help you until the next release. 
But you can still get a parse for this sentence either by disabling the POS tagger (see the parser FAQ for details on how to do this) or by using the neural network dependency parser.