sync should rethrow if stat throws (but not ENOENT)

[stefanpenner]

https://github.com/substack/node-resolve/blob/1.1.6/lib/sync.js#L9-L11

It is possible for fs.statSync to fail do for reasons other then ENOENT. As such, we should re-throw or we end up with an un-related error do to the stat object being missing: https://github.com/substack/node-resolve/blob/1.1.6/lib/sync.js#L1

note this would also fix the a-symmetry with async – which correctly handles the error https://github.com/substack/node-resolve/blob/1.1.6/lib/async.js#L23

an example would be: fs.statSync('\\\\some-unc-path\\folder name\\missing file') will throw unfortunately throw an UnknownError :(

[stefanpenner]

A followup question should be, does this mysterious UnknownError also mean "ENOENT" and should actually throw the missing module error.

Should we dig into this further upstream? What should node do here.