assumptions on writeability

I use wp-stateless https://en-ca.wordpress.org/plugins/wp-stateless/ so my wp-content is non-writable (there is more than one instance running without a shared filesystem). This can cause an issue in gutlider as below.

2025/09/10 19:13:59 [error] 93#93: *285 FastCGI sent in stderr: "PHP message: PHP Fatal error:  Uncaught TypeError: ftp_nlist(): Argument #1 ($ftp) must be of type FTP\Connection, null given in /app/wp-admin/includes/class-wp-filesystem-ftpext.php:438
Stack trace:
#0 /app/wp-admin/includes/class-wp-filesystem-ftpext.php(438): ftp_nlist()
#1 /app/wp-content/plugins/slider-blocks/includes/classes/class-generate-style.php(82): WP_Filesystem_FTPext->exists()
#2 /app/wp-includes/class-wp-hook.php(324): GutSlider_Dynamic_Style->generate_and_enqueue_combined_css()
#3 /app/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters()
#4 /app/wp-includes/plugin.php(517): WP_Hook->do_action()
#5 /app/wp-includes/script-loader.php(2299): do_action()
#6 /app/wp-includes/class-wp-hook.php(324): wp_enqueue_scripts()
#7 /app/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters()
#8 /app/wp-includes/plugin.php(517): WP_Hook->do_action()
#9 /app/wp-includes/general-template.php(3192): do_action()
#10 /app/wp-includes/template-canvas.php(17): wp_head()
#11 /app/wp-includes/" while reading response header from upstream, client: 172.17.0.1, server: _, request: "GET / HTTP/1.1", upstream: "fastcgi://unix:/run/php/php-fpm.sock:", host: "localhost"