Elf loading bug?

[cmcl]

I've been studying the elf loading procedure for SOS processes defined in elf.c. I think I've stumbled upon a bug: if the mapping fails, the frame cap is deleted and the slot is freed (the frame is also freed but is still mapped in SOS) however the code continues to use these afterwards which I expect to result in an exception around here where an attempt is made to use the frame cap.

The comment is a bit mysterious -- when it mentions all frames being mapped in, I assume it is talking about the SOS address space, but why "continue on to do the write" on a frame that's not mapped into the process' address space?