Saxon

A NullPointerException has been reported in the method MessageEmitter.endDocument(). It appears that the "writer" variable was null. Although it has not been possible to reproduce it, other related methods check that writer is not null, so it seems prudent to make a similar check in this method. The problem was observed in 9.6, although the failing code is identical in 9.5. To minimize risk, given the inability to test the fix, I will patch it only on the 9.6 and 9.7 branches, not on 9.5.