[Super Cache] exit the cache system if request uri is not set (#36024)

* Bail if the request_uri isn't set up here.

* changelog

Committed via a GitHub action: https://github.com/Automattic/jetpack/actions/runs/8082754264

CHANGELOG.md

@@ -27,6 +27,7 @@ This is an alpha version! The changes listed here are not final.
 ### Fixed
 - Supercache: add "days" to "Next preload scheduled" message.
 - Super Cache: with rebuild enabled, apply that to subdirectories instead of deleting them.
+- WP Super Cache: bail if the request uri isn't set. It means the plugin isn't configured yet.
 
 ## [1.11.0] - 2023-11-08
 ### Added

wp-cache-phase2.php

@@ -390,6 +390,11 @@ function wp_cache_postload() {
 	global $cache_enabled, $wp_super_cache_late_init;
 	global $wp_cache_request_uri;
 
+	if ( empty( $wp_cache_request_uri ) ) {
+		wp_cache_debug( 'wp_cache_postload: no request uri configured. Not running.' );
+		return false;
+	}
+
 	// have to sanitize here because formatting.php is loaded after wp_cache_request_uri is set
 	$wp_cache_request_uri = esc_url_raw( wp_unslash( $wp_cache_request_uri ) );