Yes, i think this was fixed once in the past already, i can make a workaround by setting userdata to null and ignore such bodies during material callback but i think this is probably a memory leak in the end and is probably something that can be fixed, if a deleted body is making material contact callback calls, it's still in the system somehow..
I am making a demo for you, the demo will crash at an unrelated location, but if you inspect debug log you will see a callback will be called for a body which was deleted.
DEMO: https://gtamp.com/tdc/tdc_demo_error.7z
The demo will not crash outside debugger - run with debugger, it will crash very fast without you having to do anything else.
All you need to do is run it in windbg or debug it in visual studio directly.
You can put custom newton.dll into the Libraries folder - game soft loads newton dll at runtime, it needs a 32 bit build - debug or release.
This is the same crash in visual studio with full call stack:
A deleted body had callback called:
There are other problems with the trunk newton too - it looks like optimizer deleted some parts of map and player can fall thru ground at random.. but let's first fix this as it could be the cause for other issues.