fix: visualizer getCSV method throwing constant errors (#1263)

* fix: visualizer getCSV method throwing constant errors

* fix: pr review changes

* fix: pr review changes

Author: HardeepAsrani

classes/Visualizer/Module.php

@@ -270,12 +270,15 @@ private function _getCSV( $rows, $filename, $enclose ) {
 		$bom = chr( 0xEF ) . chr( 0xBB ) . chr( 0xBF );
 		// phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged
 		$fp = function_exists( 'tmpfile' ) ? @tmpfile() : null;
-		if ( null === $fp ) {
+		if ( ! $fp ) {
 			if ( ! function_exists( 'wp_tempnam' ) ) {
 				require_once ABSPATH . 'wp-admin/includes/file.php';
 			}
 			$fp = fopen( wp_tempnam(), 'w+' );
 		}
+		if ( ! $fp ) {
+			return array( 'csv' => '', 'name' => $filename, 'string' => '' );
+		}
 		if ( ! apply_filters( 'vizualizer_export_include_series_type', true ) ) {
 			unset( $rows[1] );
 			$rows = array_values( $rows );

composer.json

@@ -52,6 +52,7 @@
     "dealerdirect/phpcodesniffer-composer-installer": "^1.0.0",
     "phpcompatibility/phpcompatibility-wp": "*",
     "phpstan/phpstan": "^2.1",
-    "szepeviktor/phpstan-wordpress": "^2.0"
+    "szepeviktor/phpstan-wordpress": "^2.0",
+    "yoast/phpunit-polyfills": "^4.0"
   }
 }