Guard fclose() against false stream in supercache-only mode (#1053)

* Guard fclose() against false stream in supercache-only mode

In supercache-only mode $fr is false (the wp-cache file is never opened). When the supercache temp file fails to open, the error branches called @fclose( $fr ) = @fclose( false ). On PHP 8+ that is a TypeError, which @ does not suppress, so the request fatals. Only call fclose() when the stream is open.

Fixes #1016.

* Silence AlternativeFunctions warning on guarded fclose calls

phpcs-changed flags the now-modified fclose() lines under WordPress.WP.AlternativeFunctions; match the file's existing inline-ignore convention for direct filesystem calls.

Author: donnchawp

wp-cache-phase2.php

@@ -2418,7 +2418,9 @@ function wp_cache_get_ob( &$buffer ) {
 			if ( ! $fr2 ) {
 				wp_cache_debug( 'Error. Supercache could not write to ' . str_replace( ABSPATH, '', $tmp_cache_filename ), 1 );
 				wp_cache_add_to_buffer( $buffer, "File not cached! Super Cache Couldn't write to: " . str_replace( ABSPATH, '', $tmp_cache_filename ) );
-				@fclose( $fr );
+				if ( $fr ) {
+					fclose( $fr ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_fclose
+				}
 				@unlink( $tmp_wpcache_filename );
 				wp_cache_writers_exit();
 				return wp_cache_maybe_dynamic( $buffer );
@@ -2430,7 +2432,9 @@ function wp_cache_get_ob( &$buffer ) {
 				if ( ! $gz ) {
 					wp_cache_debug( 'Error. Supercache could not write to ' . str_replace( ABSPATH, '', $tmp_cache_filename ) . '.gz', 1 );
 					wp_cache_add_to_buffer( $buffer, "File not cached! Super Cache Couldn't write to: " . str_replace( ABSPATH, '', $tmp_cache_filename ) . '.gz' );
-					@fclose( $fr );
+					if ( $fr ) {
+						fclose( $fr ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_fclose
+					}
 					@unlink( $tmp_wpcache_filename );
 					@fclose( $fr2 );
 					@unlink( $tmp_cache_filename );