Undefined index in shortcode.php

Hi there.
I have been finding your plugin very useful and easy to use, however I have just upgraded to php 7.2 and I am getting a whole bunch of errors:

Notice: Undefined index: yourcode in /home/%user%/public_html/wp-content/plugins/wp-download-codes/includes/shortcode.php

Notice: Undefined index: release in /home/%user%/public_html/wp-content/plugins/wp-download-codes/includes/admin/manage-codes.php on line 22

Notice: Undefined index: group in /home/%user%/public_html/wp-content/plugins/wp-download-codes/includes/admin/manage-codes.php on line 23

Notice: Undefined index: action in /home/%user%/public_html/wp-content/plugins/wp-download-codes/includes/admin/manage-codes.php on line 24

Notice: Undefined index: release in /home/%user%/public_html/wp-content/plugins/wp-download-codes/includes/admin/manage-codes.php on line 27

Notice: Undefined variable: post_prefix in /home/%user%/public_html/wp-content/plugins/wp-download-codes/includes/admin/manage-codes.php on line 175

Notice: Undefined variable: post_codes in /home/%user%/public_html/wp-content/plugins/wp-download-codes/includes/admin/manage-codes.php on line 181

Notice: Undefined variable: post_characters in /home/%user%/public_html/wp-content/plugins/wp-download-codes/includes/admin/manage-codes.php on line 187

Notice: Undefined index: import-prefix in /home/%user%/public_html/wp-content/plugins/wp-download-codes/includes/admin/manage-codes.php on line 209

Notice: Undefined index: import-codes in /home/%user%/public_html/wp-content/plugins/wp-download-codes/includes/admin/manage-codes.php on line 215

Notice: Undefined index: action in /home/%user%/public_html/wp-content/plugins/wp-download-codes/includes/admin/manage-releases.php on line 21

Notice: Undefined index: release in /home/%user%/public_html/wp-content/plugins/wp-download-codes/includes/admin/manage-releases.php on line 22

Notice: Undefined index: action in /home/%user%/public_html/wp-content/plugins/wp-download-codes/includes/admin/manage-releases.php on line 25

Notice: Undefined index: release in /home/%user%/public_html/wp-content/plugins/wp-download-codes/includes/admin/manage-releases.php on line 26

I’m really hoping you can push out an update, as I’ve given out plenty of codes and don’t want to have to downgrade to an out-of-date php.

Thanks, techybird