VASSAL has this error every time I type for the first time

So the first time I open any VASSAL module and hit a key - for whatever reason - the attached error occurs.

[attachment=1]Screen Shot 2020-04-07 at 8.37.43 AM.png[/attachment]

Running Mac OS X 10.14.6, have about twenty modules plus ten expansions in the Library.

This one’s on me - I hadn’t updated my Java install.