JSMin Errors Out

Question

When running a gulp task below I get the following error message from JSmin:

/var/www/html/a/node_modules/gulp-jsmin/node_modules/jsmin-sourcemap/node_modules/jsmin2/lib/jsmin.c.index.js:40
          stream.write(str);
                 ^
TypeError: Object function (err) {
          // Add the error to output
          options.error += err;
        } has no method 'write'
    at fputs (/var/www/html/a/node_modules/gulp-jsmin/node_modules/jsmin-sourcemap/node_modules/jsmin2/lib/jsmin.c.index.js:40:18)
    at error (/var/www/html/a/node_modules/gulp-jsmin/node_modules/jsmin-sourcemap/node_modules/jsmin2/lib/jsmin.c.index.js:89:9)
    at action (/var/www/html/a/node_modules/gulp-jsmin/node_modules/jsmin-sourcemap/node_modules/jsmin2/lib/jsmin.c.index.js:218:25)
    at jsmin (/var/www/html/a/node_modules/gulp-jsmin/node_modules/jsmin-sourcemap/node_modules/jsmin2/lib/jsmin.c.index.js:352:21)
    at main (/var/www/html/a/node_modules/gulp-jsmin/node_modules/jsmin-sourcemap/node_modules/jsmin2/lib/jsmin.c.index.js:368:9)
    at jsminFn (/var/www/html/a/node_modules/gulp-jsmin/node_modules/jsmin-sourcemap/node_modules/jsmin2/lib/jsmin.c.index.js:373:12)
    at jsmin (/var/www/html/a/node_modules/gulp-jsmin/node_modules/jsmin-sourcemap/node_modules/jsmin2/lib/jsmin.js:82:3)
    at Object.Collector.addFile (/var/www/html/a/node_modules/gulp-jsmin/node_modules/jsmin-sourcemap/lib/jsmin.sourcemap.js:24:19)
    at Array.forEach (native)
    at module.exports (/var/www/html/a/node_modules/gulp-jsmin/node_modules/jsmin-sourcemap/lib/jsmin.sourcemap.js:136:9)

/** Gulp Task **/

gulp.task('js', function() {
    gulp.src('app/assets/javascripts/**/*.js')
        .pipe(changed('public/assets/javascripts/min'))
        .pipe(jsmin())
        .pipe(rename({suffix: '.min'}))
        .pipe(gulp.dest('public/assets/javascripts/min'));

    gulp.src([  'public/assets/javascripts/min/bootstrap.min.js','public/assets/javascripts/min/jquery.flexslider.min.js','public/assets/javascripts/min/waypoints.min.min.js',
            'public/assets/javascripts/min/modernizr.custom.min.js','public/assets/javascripts/min/jquery.stapel.min.js', 'public/assets/javascripts/min/jquery.socialist.min.js',
            'public/assets/javascripts/min/enscroll.min.min.js','public/assets/javascripts/min/jquery-ui-1.8.2.custom.min.min.js','public/assets/javascripts/min/pirobox_extended_min.min.js',
            'public/assets/javascripts/min/jquery.masonry.min.min.js', 'public/assets/javascripts/min/functions.min.js'])
        .pipe(concat('application.js'))
        .pipe(gulp.dest('public/assets/javascripts/min/'));
});

Could someone help me figure out what's going on?

Answer 1

The short answer is that the node-jsmin2 module has a bug in it, introduced since revision 7d5f486f46b453d738057e97060e4805846bf4af.

In that revision, fputs was modified to call stream.write(str) instead of stream(str), and stdout was modified to be an object containing write and writeFromIndex methods—but stderr was not similarly modified. (That commit, BTW, means that the defaults for stdout and stderr, namely console.log and console.error, are no longer suitable. This has been alluded to in the TODO.md change in that commit.)

Here's a quick "fix" (I contemplated sending a pull request, but decided against it):

diff --git a/lib/jsmin.js b/lib/jsmin.js
index 439957b..c6f9331 100644
--- a/lib/jsmin.js
+++ b/lib/jsmin.js
@@ -68,9 +68,11 @@ function jsmin(input) {
             output += char;
           }
         },
-        'stderr': function (err) {
-          // Add the error to output
-          options.error += err;
+        'stderr': {
+          'write': function (err) {
+            // Add the error to output
+            options.error += err;
+          }
         },
         'exit': function (code) {
           // Throw the collective error