执行glup 报错

[w19871029]

执行glup 报错

path.js:116

Arguments to path.resolve must be strings

结构是

package.json

    {
      "name": "gulp",
      "version": "2.0.0",
       "main": "index.js",
       "dependencies": {
           "gulp": "^3.8.10",
           "gulp-util": "^3.0.1"
         },
        "devDependencies": {
             "gulp": "^3.8.10",
             "gulp-util": "^3.0.1",
             "gulp-uglify": "^1.0.1",
             "gulp-concat": "^1.0.0"
          },
         "scripts": {},
         "author": "",
         "license": "ISC"
         }

gulpfile.js

var gulp    = require('gulp');
var gutil    = require('gulp-util');
var uglify  = require('gulp-uglify');
var concat  = require('gulp-concat');

gulp.task('concat', function(){
     gulp.src('./js/*.js')
     .pipe(uglify())
     .pipe(concat('all.min.js'))
     .pipe(gulp.dest('./build'));
 });
 gulp.task('default', ['concat']);