A system has an Ace which specifies a visible class FOO, where FOO is
reachable from the root class.  After initial compilation where the
system is frozen or finalized, a local is removed, making class FOO
unreachable from the root.  When the system is recompiled, the
compiler correctly detects the VD31 error.  But when the local is
added back in and compilation is resumed, the compiler dies during
degree -3 (during dead code removal if system was finalized).

Discovered in Release 3.3.7.