Skip rewriting when file contents are empty

Author: john-shaffer

src/SimpleRewriter.php

@@ -56,10 +56,10 @@ public static function rewrite( string $filename ) : void {
 
         if ( $file_contents === false ) {
             $file_contents = '';
+        } else {
+            $rewritten_contents = $rewriter->rewriteFileContents( $file_contents );
         }
 
-        $rewritten_contents = $rewriter->rewriteFileContents( $file_contents );
-
         file_put_contents( $filename, $rewritten_contents );
     }