Found while analyzing JDK-8361342:

`ShenandoahAsserts::print_obj()` does not work for COH if the object is forwarded, since the mark word is overwritten with forwarding pointer.

Depending on the size of the numerical address of the forwardee nKlass either appears to be zero, resulting in "assert(!is_null(v)) failed: narrow klass value can never be zero", or some garbage value if it overlaps with the nKlass bits, in which case we get a SIGSEGV.