Gutenberg issue when editing

Hi All

I am not sure if this happened since I updated my storefront Version: 2.4.0 them this morning but getting this error when trying edit using gutenberg any ideas?

Fatal error: Using $this when not in object context in /home/fantas64/public_html/wp-content/themes/storefront/inc/customizer/class-storefront-customizer.php on line 906

I have tried removing the plugin and re-installing any ideas very much appreciated

The page I need help with: [log in to see the link]