Feature description
when the read of 'extra-keys' setting fails[ie, bad JavaScript format], have the default keybar appear. currently the app shows a bar with nothing: a blank black bar with no ctrl or fntn keys.

if the user uses emacs to edit the settings file, this results in a terminal that we cannot do anything in if emacs is in the foreground, [ctrl is reqired at the least with emacs] thus effectively locking the terminal.

a hacky workaround is to then open another terminal and 'kill -9' the running emacs, and then mv or delete the faulty properties file, ... or use a different editor that doers not require ctrl and esc to work.

loading a blank bar is worse than the default key bar, and the default is easy to load instead, just do the same thing as when the settings file is not there.

Reference implementation
none, n/a