Better diagnostic error message when encountering a git-lfs placeholder file

[permcody]

Reason

If you checkout a repository on a system that doesn't have git-lfs installed or enabled. You will get placeholder files for any files that are stored in git-lfs data stores. Those files contain plain ASCII text like this:

version https://git-lfs.github.com/spec/v1
oid sha256:3b7a78871b902e28e46756241a510dcb72de8f3eb2dd3d5bc31342085f1976ed
size 145124

The problem is that this confuses some of the readers in MOOSE. In particular we sometimes store large mesh files like this in which case the user will get a message like this:

*** ERROR ***
Error opening ExodusII mesh file: /Users/johndoe/projects/foo/problems/big_mesh.e

This occurs even if the file is there.

Design

We already have utility routines that check for file readability or writeability before trying to interpret data. We are fairly consistent with calling these. I would propose that we add another utility routine that specifically checks for git-lfs placeholder files that we can call from the readability routine. We could then issue a much more useful error and potentially helpful diagnostic message that could help a user recover without seeking assistance from the developer community.

Impact

None, moderate annoyance.

[WilkAndy]

Yep, this stumped me a while ago. Not a big deal, but confusing.

[permcody]

Closed by #17489