Also have special error handling for when branches are invalid and
ENOENT would be returned for getattr and readdir so users understand
what is going on and the runtime interface can still be used to fix
the problem.
chmod, chown, removexattr, setxattr, truncate, utimens:
* if no errors: return 0
* if no successes: return first error
* if file acted on was the same as related search function: return its value
* return 0
rmdir, unlink:
* if no errors: return 0
* return first error