Summary:
Errors and warnings are both shown to users. I'm applying the rule of
thumb of using errors for non-recoverable problems that require *our*
intervention. All of these errors can happen under normal
circumstances.
Reviewed By: mweststrate
Differential Revision: D26577917
fbshipit-source-id: 12ba6725b6575bdf62141b01a16a5638c2c95701