gulp task `lint-templates` to lint Aurelia templates (also shows UI notification when there is a problem or when all problems are fixed)

aurelia-template-lint.js

var gulp = require('gulp');
var linter = require('gulp-aurelia-template-lint');
var config = new (require('aurelia-template-lint').Config);
var fail = require('gulp-fail');
var gulpIf = require('gulp-if');
var gutil = require('gulp-util');
var notify = require("gulp-notify");

var paths = require('../paths');

config.useRuleAureliaBindingAccess = true;
config.reflectionOpts.sourceFileGlob = "aurelia/src/**/*.ts";
config.reflectionOpts.typingsFileGlob = "typings/**/*.d.ts";
config.aureliaBindingAccessOpts.restrictedAccess = ["private"]; // using "protected" for fields that are used in html
/*
 config.debug = true;
 */

var hadErrors = false; // used when task is executed many times (`gulp watch`)
gulp.task('lint-templates', function() {
  var errorsCount = 0;
  var reporter = (error, file) => {
    if (error.severity > 1) {
      errorsCount++;
    }
    var [severity, color] = getSeverityText(error);
    var msg = `${severity}: ${error.message} - ${file}(${error.line}:${error.column})`;
    gutil.log(color(msg));
  };
  return gulp.src(paths.src.html)
    .pipe(linter(config, reporter))
    .pipe(
      gulpIf(
        () => {
          return errorsCount !== 0;
        },
        fail(
          () => {
            hadErrors = true;
            const msg = `Found ${errorsCount} errors when linting HTML templates`;
            notify({
              title: "gulp lint-templates",
              message: msg,
            }).write('');
            return msg;
          },
          true
        )
      )
    )
    .on('end', function() {
      if (hadErrors && errorsCount === 0) {
        hadErrors = false;
        notify({
          title: "gulp lint-templates",
          message: "all errors fixed",
        }).write('');
        hadErrors = false;
      }
    });
});

function getSeverityText(issue) {
  if (issue.severity === 0) {
    return ["INFO", gutil.colors.green];
  } else if (issue.severity === 1) {
    return ["WARNING", gutil.colors.yellow];
  } else if (issue.severity === 2) {
    return ["ERROR", gutil.colors.red];
  } else if (issue.severity === 3) {
    return ["FATAL", gutil.colors.magneta];
  } else {
    return ["SEVERITY " + issue.severity, gutil.colors.red];
  }
}