MsgQueue: change assertion to conditional
MsgQueue: change assertion to conditional

This guards against the situation where a message is recycled wtihout having been queued. This is happening somewhere in AlloSystem.

AlloSphere-Research-Group/AlloSystem,AlloSphere-Research-Group/AlloSystem,AlloSphere-Research-Group/AlloSystem,AlloSphere-Research-Group/AlloSystem,AlloSphere-Research-Group/AlloSystem