thanks for reporting this. Your problem only occurs since the missing method was added (before PFAW only returned some default, now it throws NPE) in that case.
In general, Lucene does not support null analyzers anywhere (not as ctor argument in IW/IWC) or e.g. here. You should always add a "simple" analyzer to IndexWriter (WhitespaceAnalyzer, SimpleAnalyzer, KeywordAnalyzer) or other methods taking Analyzer.
To really fix this, we have to review all places that don't need to call Analyzers. There are e.g. other places, like when you directly pass the TokenStream to the Field with "new Field(name, TokenStream), it also calls the analyzer, so you have to implement it.