Fix a discrepancy in the error message for DirectoryError::SizeOverflow.
The message indicates that the SizeOverflow error occurs when total size
exceeds u32::MAX, but that's not true. All size fields within the
castore's internal Directory ADT are u64, and the SizeOverflow error is
only returned after a call to the checked_add implementation on u64.
See tvix/castore/nodes/directory.rs +111
and tvix/castore/nodes/directory.rs +88
as of this commit.
Change-Id: I74d161ea8927362e1cb601ba163489aa96fb91b1
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12259
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>