Missing file causes critical error

I’ve found this error in the log of a client’s site and checked the source. The mentioned file is indeed missing in the plugin:

Een fout van het type E_ERROR werd veroorzaakt op regelnummer 158 van het bestand /.../wp-content/plugins/wc-thanks-redirect/src/Modules/SandBoxPayment.php. Foutmelding: Uncaught Error: Failed opening required '/.../wp-content/plugins/wc-thanks-redirect/src/Modules/SandBoxPaymentBlocksSupport.php' (include_path='.:/usr/local/php83/lib/php') in /.../wp-content/plugins/wc-thanks-redirect/src/Modules/SandBoxPayment.php:158
Stack trace:
#0 /.../wp-includes/class-wp-hook.php(324): NeeBPlugins\Wctr\Modules\SandBoxPayment->NeeBPlugins\Wctr\Modules\{closure}()
#1 /.../wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters()
#2 /.../wp-includes/plugin.php(517): WP_Hook->do_action()
#3 /.../wp-content/plugins/woocommerce/src/Blocks/Integrations/IntegrationRegistry.php(50): do_action()
#4 /.../wp-includes/class-wp-hook.php(324): Automattic\WooCommerce\Blocks\Integrations\IntegrationRegistry->initialize()
#5 /.../wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters()
#6 /.../wp-includes/plugin.php(517): WP_Hook->do_action()
#7 /.../wp-settings.php(727): do_action()
#8 /.../wp-config.php(96): require_once('...')
#9 /.../wp-load.php(50): require_once('...')
#10 /.../wp-admin/admin.php(35): require_once('...')
#11 /.../wp-admin/post.php(12): require_once('...')
#12 {main}