Fatal Error after Theme Installation

Hello all,
Please forgive me – I am new to this..
I have set up a wordpress site locally on my computer, and when I have tried to link it to a new theme (Granola). My website no longer loads and instead comes up the below

In the error it says it is thrown on line 10 of admin.php, but that line is empty in my code

Has anyone come across this before? Any help would be SO much appreciated

Fatal error: Uncaught TypeError: Return value of Granola\WordPress\Admin::init() must be an instance of Granola\WordPress\void, none returned in /var/www/public/wp-content/themes/your-theme-name/granola/wordpress/admin.php:10 Stack trace: #0 /var/www/public/wp-content/themes/your-theme-name/granola/granola.php(31): Granola\WordPress\Admin::init() #1 /var/www/public/wp-content/themes/your-theme-name/functions.php(11): require_once(‘/var/www/public…’) #2 /var/www/public/wp-settings.php(514): include(‘/var/www/public…’) #3 /var/www/public/wp-config.php(90): require_once(‘/var/www/public…’) #4 /var/www/public/wp-load.php(37): require_once(‘/var/www/public…’) #5 /var/www/public/wp-blog-header.php(13): require_once(‘/var/www/public…’) #6 /var/www/public/index.php(17): require(‘/var/www/public…’) #7 {main} thrown in /var/www/public/wp-content/themes/your-theme-name/granola/wordpress/admin.php on line 10
There has been a critical error on your website.