[...]
Based on that output, it's hard for me to tell what about "open-package'" failed
Yup. What I spot:
: mount-root ( Empty ) 00000000ffe35d28: boot-dev$ ( ffe357a8 6 ) 00000000ffe35d30: fs-pkg$ ( ffe357a8 6 ffe317c0 10 ) 00000000ffe35d38: $open-package : $open-package ( ffe357a8 6 ffe317c0 10 )
It looks like fs-pkg$ names the package it's opening. I'm guessing that's hsfs-file-system, but you should probably verify that's what is in that string (do a "2dup type" before calling $open-package). If that's correct, then rather than descending into open-package, you probably want to put a breakpoint at "open" in /packages/hsfs-file-system, which is where that will end up after much wandering around. Then proceed from there - you really don't want to trace through instance creation.
The reason you weren't able to see all that (which would have been overwhelming) is a bit further down:
00000000ffe135f0: (lit) ( 1 ffe2fe38 ffe4b1d8 ffe4b548 ffe135e0 4 ffe4b558 ffe13310 ) 00000000ffe13600: catch ( 1 ffe2fe38 ffe4b1d8 ffe4b548 ffffffffffffffff 0 )
That's basically a subroutine call to ffe13310, which it didn't show.