How do I fix this error?
Error trying to parse settings: No data in ~/Library/Application Support/Sublime Text 2/Packages/User/JavaScript.sublime-settin
Most likely you or something has created an empty file in your User config directory.
The config files must be valid JSON. The file in the question is empty and is not JSON.
Try deleting the file or get a fixed version from somewhere (not sure for what the file is being used for)