Clean up `bundle_path()` error handling

[colearendt]

• [ ] check that manifest.json is in the tar archive:

"./manifest.json" %in% utils::untar(filepath, list = TRUE)

• [ ] check that the filetype is a .tar.gz? Not sure how to do this...
• [ ] check that file actually exists

Could put some of these checks into the Bundle R6 class if we want too...

[brooklynbagel]

check that manifest.json is in the tar archive:

I've noticed when using download_bundle, sometimes it is "manifest.json" and other times it is "./manifest.json" that is present. I don't know why, but I wonder if this can the case depending on how the tarball is created?

check that the filetype is a .tar.gz? Not sure how to do this...

Is this just making sure the file at filepath is just a valid tarball? Can we just list the contents and if that fails bail out?

check that file actually exists

Is this just checking that there is actually a file at filepath?