error in running

Starting 'compile-coffee'...
[01:19:02] Finished 'compile-coffee' after 14 ms

stream.js:94
      throw er; // Unhandled stream error in pipe.
            ^
Error: [stdin]:31:22: error: reserved word "static"
            position static
                     ^
  at Stream.modifyFile (../node_modules/gulp-coffee/index.js:37:33)

gulpfile.js

var gulp = require('gulp'),
  coffee = require('gulp-coffee');

// task
gulp.task('compile-coffee', function () {
    gulp.src([
        'client/**',
        'server/**',
        'model/**',
        'tests/**',
      ])
    .pipe(coffee())
    .pipe(gulp.dest('./'));
});

File running and fixed
var gulp = require('gulp'),
coffee = require('gulp-coffee'),
gutil = require('gulp-util'),
stylus = require('gulp-stylus');

// tasks
gulp.task('client-stylus', function () {
gulp.src('client/*.styl')
.pipe(stylus())
.pipe(gulp.dest('./client'));
});

gulp.task('client', function () {
gulp.src('client/*.coffee')
.pipe(coffee({bare: true}).on('error', gutil.log))
.pipe(gulp.dest('./client'));
});

// gulp.task('client', function () {
// gulp.src([
// 'client/',
// '!client/compatibility/',
// '!client/.styl',
// '!client/.html',
// ])
// .pipe(coffee({bare: true}).on('error', gutil.log))
// .pipe(gulp.dest('./client'));
// });

gulp.task('server', function () {
gulp.src('server/**')
.pipe(coffee({bare: true}).on('error', gutil.log))
.pipe(gulp.dest('./server'));
});

gulp.task('model', function () {
gulp.src('model/**')
.pipe(coffee({bare: true}).on('error', gutil.log))
.pipe(gulp.dest('./model'));
});

gulp.task('tests', function () {
gulp.src('tests/**')
.pipe(coffee({bare: true}).on('error', gutil.log))
.pipe(gulp.dest('./tests'));
});

gulp.task('default', ['client', 'client-stylus', 'server', 'model', 'tests']);