I had some problems after I installed this with the current XAMPP install. the expression engine has been updated and to use your "oldschool" expression you have to turn them on. Also found a dependency that you may want to turn on. Here is how I start my htaccess file now:

Start FancyDir Config

SSILegacyExprParser on
Options +Indexes +Includes

This will correct the [an error occurred while processing this directive] that happens when trying to execute your SHTML expressions in fancydir.

Hello,

After all those years there is still interest in your theme.

I'm getting the following error:

javascript.js:76 Uncaught TypeError: Cannot read properties of null (reading '1')
    at javascript.js:76:59
    at javascript.js:84:3