The files preferences.xhtml and preferences.js are missing in the src-2.0 directory. These files are referred to in bootstrap.js in the same directory. Their absence causes the following error in the error console on clicking on the preference pane for the extension:
Uncaught (in promise) Error opening input stream (invalid filename?): file:///home/<snip>/make-it-red/src-2.0/preferences.js
The files
preferences.xhtmlandpreferences.jsare missing in thesrc-2.0directory. These files are referred to inbootstrap.jsin the same directory. Their absence causes the following error in the error console on clicking on the preference pane for the extension: