assert("narrow oop can never be zero") for GCBasher & ParNewGC

Very sporatic GCBasher bugs with this assert.
eval C:/jprt/temp/P1/T/192955.rasbold/testproduct/windows_x64_5.2-fastdebug/bin/java
  -server -Xmx128M -XX:+UseParNewGC -jar GCBasher.jar -time:300000 )
# To suppress the following error report, specify this argument
# after -XX: or in .hotspotrc: SuppressErrorAt=\oop.inline.hpp:147
#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (C:\jprt\temp\P1\B\192955.rasbold\source\src\share\vm\oops\oop.inline.hpp:147),
  pid=2628, tid=3224
# Error: assert(!is_null(v),"narrow oop value can never be zero")
#
# Java VM: Java HotSpot(TM) 64-Bit Server VM
  (12.0-b02-2008-04-22-192955.rasbold.hotspot-comp-clean-fastdebug mixed mode
  windows-amd64 compressed oops)
# An error report file with more information is saved as:
# C:\jprt\products\P1\GCBasher\hs_err_pid2628.log
#
# If you would like to submit a bug report, please visit:
# http://java.sun.com/webapps/bugreport/crash.jsp
#
VM option '+UseParNewGC'

Decoded hs_err file attached.