While processing todays batch of data we got a Nullpointer exception in getLeftSideBearing. Sadly I can't give you the PDF.
public int getLeftSideBearing(int gid)
In this function there could be a case where nonHorizontalLeftSideBearing is null and you still ask for a GID in larger or equal to numHMetrics.
First time I see this issue and so far only 4 characters in one PDF has this issue so not critical.