PHP Fatal Error: Call to a member function exists() on null

[uamv]

Hello! I've finally got around to testing 1.0.8, as a client is looking to upgrade a PHP version. However, I'm encounter the following fatal error when attempting to enter API credentials.

PHP Fatal error:  Uncaught Error: Call to a member function exists() on null in /home/.../wp-content/plugins/church-community-builder-core-api/includes/class-ccb-core-helpers.php:199, referer: https://.../wp-admin/admin.php?page=ccb_core_settings_api_settings
mod_fcgid: stderr: Stack trace:, referer: https://.../wp-admin/admin.php?page=ccb_core_settings_api_settings
mod_fcgid: stderr: #0 /home/.../wp-content/plugins/church-community-builder-core-api/includes/class-ccb-core-helpers.php(116): CCB_Core_Helpers->save_encryption_key('......'), referer: https://.../wp-admin/admin.php?page=ccb_core_settings_api_settings
mod_fcgid: stderr: #1 /home/.../wp-content/plugins/church-community-builder-core-api/includes/class-ccb-core-settings.php(110): CCB_Core_Helpers->encrypt('...'), referer: https://.../wp-admin/admin.php?page=ccb_core_settings_api_settings
mod_fcgid: stderr: #2 /home/.../wp-includes/class-wp-hook.php(289): CCB_Core_Settings->validate_settings(Array), referer: https://.../wp-admin/admin.php?page=ccb_core_settings_api_settings
mod_fcgid: stderr: #3 /home/.../wp-includes/plugin.php(206): WP_Hook->apply_filters(Array, Array), referer: https://.../wp-admin/admin.php?page=ccb_core_settings_api_settings
mod_fcgid: stderr: #4 /home/.../wp-includes/formatting.php(4845): apply_filters('sanitize_option...', Array, 'ccb_core_settin...', Array), referer: https://.../wp-admin/admin.php?page=ccb_core_settings_api_settings
mod_fcgid: stderr: #5 /home/.../wp-includes/option.php(318): sanitize_o in /home/.../wp-content/plugins/church-community-builder-core-api/includes/class-ccb-core-helpers.php on line 199, referer: https://.../wp-admin/admin.php?page=ccb_core_settings_api_settings

Any insights?