Java 14 "Helpful NullPointerExceptions"

There is a great option to add in pljava.vmoptions when running on
Java 14 or later:

-XX:+ShowCodeDetailsInExceptionMessages

It arranges so that if a NullPointerException is ever thrown, instead of

ERROR: java.lang.NullPointerException

you see something like

ERROR: java.lang.NullPointerException: Cannot assign field "i" because
"a" is null

A little thing, but handy, and very easy to enable. It doesn't add to the
cost of null-pointer exceptions thrown and caught internally, because the
work is only done if the message is used. [1]

-Chap

[1] https://openjdk.java.net/jeps/358