One could argue, as outlined in How to report problems, that you should have attached the errorLog when reporting the problem in the first place. In fact, the errorLog provides more useful information than a screenshot of the problem.
You should be able to reproduce the problem and then capture the errorLog - not difficult in “real life”.
Remember, you need to help others so that they can help you.
Did increasing the allocated memory for the virtual machine solve your issue?
Vassal using ~6GB of memory sounds like you’ve stumbled upon a memory leak triggered by the module you are using - which you should also have reported, btw - and the errorLog may point people in-the-know in the right direction.
The problem of shutting down Vassal when it hits a memory leak is quite general of Java due to the garbage collection done in the virtual machine and due to how Java handles the exception stack. It is not easy to work around that in an application.
Please help others help you by providing enough information (see How to report problems) to facilitate a diagnostic. Thanks.
Yours,
Christian