Use use so closure has access to variable from parent scope

Author: coffee2code

lib/runner.php

@@ -155,7 +155,7 @@ function fix_newlines( $text ) {
 	// Replace newline characters within 'code' and 'pre' tags with replacement string.
 	$text = preg_replace_callback(
 		"/(?<=<pre><code>)(.+)(?=<\/code><\/pre>)/s",
-		function ( $matches ) {
+		function ( $matches ) use ( $replacement_string ) {
 			return preg_replace( '/[\n\r]/', $replacement_string, $matches[1] );
 		},
 		$text