I don’t know a lot.
unpackfs would be unpack file system.
mount error code 32 means it failed to mount the disk.
What were the steps you have done during the installer to get to here?
Source code but does not help
It would probably also be useful to know what hardware you are trying to install on - Librem laptop, something else? And whether you already have another OS installed or not.
From the traceback, it says that it couldn’t mount the file system. What hardware are you using? What image are you using?
I have no intention to try to fix this but something same/similar was already discussed on lubuntu forum (with post 28 offering solution).