Catch save errors

It looks like this package calls `TextEditor::save` and doesn't catch the errors possibly thrown while writing the file to disk which can be numerous given all the IO failures possible.

It looks like these errors are being reported to core Atom because of the stack trace depth is capped to 10 lines and so the call sites from this package aren't included.

See https://github.com/atom/atom/issues/7836 for an example. Apologies if this isn't actually happening here.