Version 1.5 appears to be missing files on WP Packagist – fatal error

Luckily I have found a copy of 1.3, which I have put onto GitHub at garymarkfuller/-WC-Custom-Add-to-Cart-Labels-Backup: A backup of version 1.3 of the plugin as version 1.5 currently causes WordPress sites to experience a critical error. I would recommend overwriting the existing plugin files with these and altering any reference to version 1.3 in them to version 1.5. You should then find the plugin will work again and should also be able to easily upgrade to the next version from the plugin author which I hope will fix the problem.