Sometimes get worktree failure error for folder session

[bamurtaugh]

My CLI AHP sessions have been kicking off successfully today, but I got one error while kicking off a new one:

Error: (sendFailed) Error: git worktree exited with code 128: fatal: Could not reset index file to revision 'HEAD'.

Interestingly, this happened for a folder (non-worktree) session. @karthiknadig is getting this repeatedly too (I think he got this for every session he tried to kick off, whereas I only got it 1 in maybe 10 sessions).

[connor4312]

There is also a failure mode if git is init'd in a folder but there are no commits yet. We should fail gracefully here like we do in local EH, and also probably not offer worktrees for empty init or other cases where we know we can't create a worktree