v0.11.0

Breaking changes

• Switched to treating blank responses (empty or whitespace-only) like other errors. They no longer update stored data. However, they now produce a distint "blank response" error with --verbose. There doesn't seem to be a practical benefit to distinguishing between these and other invalid responses (beyond a special error), and a blank document isn't valid JSON according to RFC 8259. (JSON-text = ws value ws; value is mandatory.)