Javascript 复制文件时gulp出错

输入gulp watch命令时，我的命令行显示以下错误。因为gulp是从应用程序目录中搜索css文件，而不是从bower_组件中搜索。我尝试过使用minify css和copy-css。两者都不起作用

events.js:160
  throw er; // Unhandled 'error' event
  ^
Error: Path F:\Backup Folder\coursera-project\Full stack course\Angular Js\Assignments\week1\confusion\app\bower_components\bootstrap\dist\css\bootstrap.min.css not found!

我的gulpfile.js文件

'use strict';
var gulp = require('gulp'),
cleancss = require('gulp-clean-css'),
jshint = require('gulp-jshint'),
stylish = require('jshint-stylish'),
uglify = require('gulp-uglify'),
usemin = require('gulp-usemin'),
imagemin = require('gulp-imagemin'),
rename = require('gulp-rename'),
concat = require('gulp-concat'),
notify = require('gulp-notify'),
cache = require('gulp-cache'),
changed = require('gulp-changed'),
rev = require('gulp-rev'),
browserSync = require('browser-sync'),
del = require('del'),
ngannotate = require('gulp-ng-annotate');

gulp.task('jshint', function() {
return gulp.src('app/scripts/**/*.js')
.pipe(jshint())

  .pipe(jshint.reporter(stylish));
});

// Clean
gulp.task('clean', function() {
    return del(['dist']);
});

// Default task
gulp.task('default', ['clean'], function() {
    gulp.start('usemin', 'imagemin','copyfonts');
});

gulp.task('usemin',['jshint'], function () {
  return gulp.src('./app/**/*.html')
    .pipe(usemin({
      css:[cleancss(),rev()],
      js: [ngannotate(),uglify(),rev()]
    }))

    .pipe(gulp.dest('dist/'))

});

// Images
gulp.task('imagemin', function() {
  return del(['dist/images']), gulp.src('app/images/**/*')
    .pipe(cache(imagemin({ optimizationLevel: 3, progressive: true, interlaced: true })))
    .pipe(gulp.dest('dist/images'))
    .pipe(notify({ message: 'Images task complete' }));
});

gulp.task('copyfonts', ['clean'], function() {
   gulp.src('./bower_components/font-awesome/fonts/**/*.{ttf,woff,eof,svg}*')
   .pipe(gulp.dest('./dist/fonts'));
   gulp.src('./bower_components/bootstrap/dist/fonts/**/*.{ttf,woff,eof,svg}*')
   .pipe(gulp.dest('./dist/fonts'));
});

// Watch
gulp.task('watch', ['browser-sync'], function() {
  // Watch .js files
  gulp.watch('{app/scripts/**/*.js,app/styles/**/*.css,app/**/*.html}', ['usemin']);
      // Watch image files
  gulp.watch('app/images/**/*', ['imagemin']);

});

gulp.task('browser-sync', ['default'], function () {
   var files = [
      'app/**/*.html',
      'app/styles/**/*.css',
      'app/images/**/*.png',
      'app/scripts/**/*.js',
      'dist/**/*'
   ];

   browserSync.init(files, {
      server: {
         baseDir: "dist",
         index: "index.html"
      }
   });
        // Watch any files in dist/, reload on change
  gulp.watch(['dist/**']).on('change', browserSync.reload);
    });  

---

我也无法将html文件复制到我的dist文件夹。

奇怪，您的控制台清楚地显示“bootstrap.min.css未找到！”在发布queyes@VinodLouis之前阅读错误，但我的目录中有一个bootstrap.min.css文件。我确信在搜索文件时gulp中存在问题。