tmpfs mounts but is not writeable. iSH instacrashes if unmounted

This was tested on latest Test Flight stock FS as of the day this is posted.

tmpfs can be mounted, but creating any file/dir there just reports: File name too long

When you unmount the tmpfs, iSH instantly craches and the app is closed without the question if you want to report the crash.

No source files, tests, or entry points are named. Reproduce the tmpfs write failure and unmount crash in the iSH TestFlight build; done means tmpfs accepts file and directory creation and unmounting no longer closes the app.

Written by the indexing model from the issue text.