monitor errors will SEGVthe interpreter

From chan@scndprsn Mon Nov 14 13:49 PST 1994
Date: Mon, 14 Nov 1994 13:40:10 +0800
From: chan@scndprsn (Patrick P. Chan)
To: csw@scndprsn, eugene@scndprsn, lindholm@scndprsn
Subject: monitorExit

If mid == MID_NULL, SignalError is called. However, when SignalError
returns, mid is promptly deferenced. This a bug?

The other monitor routines are also coded similarly.

Cheers,
Pat