title: Gulp streamqueue sass plumber watch. Errors breaks task
body: <p>Have a problem occurs with gulp task using the Streamqueue, sass, plumber and watching it at the end.
  The Task is compiling production css-file from vendors css|scss files with my own.</p>
  
  <pre><code>gulp.task('fincss', function () {
      watch([workData.sassSrcFiles, workData.cssVendorSrcFiles], {}, function () {
          var convertFromScssToCssAndConcat =
              gulp.src(workData.sassSrcFiles)
                  .pipe(plumber(error))
                  .pipe(sass());
  
          var minifyAndConcatExistingCss =
              gulp.src(workData.cssVendorSrcFiles)
                  .pipe(plumber(error));
  
          return sq({objectMode: true}, minifyAndConcatExistingCss, convertFromScssToCssAndConcat)
              .pipe(concat('final.min.css'))
              .pipe(uglifycss())
              .pipe(gulp.dest(workData.cssDest))
              .pipe(livereload());
      });
  });
  
  var error = function (e) {
      console.error('Error in plugin "' + e.plugin + '"');
      console.error('   "' + e.message + '"');
      console.error('   In file "' + e.fileName + '", line "' + e.lineNumber + '".');
      console.log('--------------------------------------');
      console.log(e);
  };
  </code></pre>
  
  <p>But when error in scss file then breaking task. And any experiments with plumber which provides in Internet doesn't helps me anyway. Something like inserting plumber() before <code>concat</code>, or using <code>this.emit('end')</code> in the error handler do nothing.</p>
  
  <p>In other my tasks like </p>
  
  <pre><code>gulp.task('toHtml', function () {
      watch(workData.pugSrcFiles, {}, function (e) {
          message('Start generating template.');
          gulp.src([workData.pugSrcFiles, '!' + workData.pugSrc + '_*.pug'])
              .pipe(plumber(error))
              .pipe(pug({pretty: true}))
              .pipe(gulp.dest(pubDir))
              .pipe(livereload());
      });
  });
  </code></pre>
  
  <p>all works pretty good and without breaking task.</p>
  
  <p>Help, please.</p>