Error: O Invalid Opcode with Virtual WuObjects Update function calls()

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I noticed that virtual wuobjects update function calls could cause Error: O after running for awhile.

I don't know the cause yet, but it happens consistently.

How to reproduce:

1. git pull (my current commit hash is: fe24e66)
2. go to java/example/FurExample.java and change the application so that initializeWuObjects will create virtual wuobjects on the nodes that you are using (change the node ids)
3. go to vm/build/avr_mega2560/ and type make avrdude and update the new VM code to all your test nodes (I recommend at least 3 nodes for this application)
4. Let it run for a bit, then you should see the Error: O

I hypothesized that it could be stack overflow, and that might explain why it happens only running after awhile, but I have no idea how to fix it.