Update util.js (#173)

Wrong variabe used (another)

Author: ripkens

lib/util.js

@@ -128,7 +128,7 @@ function runExecIntoFile( label, filePath, options, execOptions, genCommand, cb
           fs.readFile( fileTempOutPath + '.txt', 'utf8', function( error2, text ) {
             if ( error2 ) {
               error2 = new Error( 'Error reading' + label +
-                ' output at [[ ' + fileTempOutPath + ' ]], error: ' + error.message );
+                ' output at [[ ' + fileTempOutPath + ' ]], error: ' + error2.message );
               cb( error2, null );
             } else {
               fs.unlink( fileTempOutPath + '.txt', function( error3 ) {