Bug, WP_CACHE left behind in wp-config.php

The line define( 'WP_CACHE', true ); is not removed from wp-config.php after deactivation / deletion of plugin.

As a sidenote we would recommend better handling of return codes of functions, e.g. when dealing with wp-config.php in surge/include/install.php:

$config = file_get_contents( $config_path );
$pattern = '..removed..';
$config = preg_replace( $pattern, '', $config );

$bytes = file_put_contents( $config_path, $config );
update_option( 'surge_installed', $bytes ? 1 : 2 );

Theoretical code flow:

If $config is false from file_get_contents() it will be empty at file_put_contents() which can return 0 written bytes which will write 2 in surge_installed which somewhere else might be interpreted as write-permission problem but actually isn’t.

Not sure if this can ever happen, the recommendation comes from experience with typical problems which can arise when not checking return codes and/or not with identical comparison operator.

WordPress 5.8.2, Twenty Twenty-One 1.4, Surge 1.0.1