Error while executing command "gulp browser-sync" Couldn't open browser?

Question

gulp.js

Hello.
Just started getting to know gulp.
I decided to screw browserSync and ran into an error

. Here is the gulpfile.js code itself

var gulp 		= require('gulp'),
  sass 		= require('gulp-sass'),
  browserSync = require('browser-sync');

gulp.task('sass', function() {
  return gulp.src('app/sass/**/*.sass')
  .pipe(sass())
  .pipe(gulp.dest('app/css'))
});

gulp.task('watch', function() {
  gulp.watch('app/sass/main.sass', gulp.parallel('sass'));
});

gulp.task('browser-sync', function() {
  browserSync.init({
    server: {
      baseDir: 'app'
    },
    notify: false,
  });
});

Tell me what's wrong.
The decision of type to specify the browser or to replace port did not help. I would be very happy if someone could give me a hint.
browser: 'chrome'
browser:'chrome.exe'
port: '8080'