Grunt: Warning: Object #<Object> has no method 'indexOf'

Question

So, I've recently started using Grunt, and it's working! Great.

As I use LESS, I decided I want development and production version of the compiled CSS - so I decided to add in the relevant targets. However, I'm now getting the error specified in the title.

I've looked at StackOverflow, and a lot of the solutions are regarding the [] around the 'files' option(is that the right word?), which I lack. I don't know where in the file I need to add them, and I've tried some places and it doesn't work.

Adding [] to the 'src' option I have doesn't work either.

Here's the first part of my Gruntfile - I don't believe the rest is needed.

module.exports = function(grunt) {

grunt.initConfig({

   pkg: grunt.file.readJSON('package.json'),
   less: { 
    production: { 
        options: { 
            path: ["css"], 
            cleancss: true 
    }, 

     src: {
        expand: true,
        cwd:    "css/",
        src:    ['*.less', '!_*.less'],
        dest:   "production/css/", 
        ext:    ".css"
}   
 }, 

 dev: {
   options: { 
    path: ["css"] 
}, 

src: { 
        expand: true,
        cwd:    "css/",
        src:    ['*.less', '!_*.less'],
        dest:   "css/", 
        ext:    ".css"
}
   }

         }, 

Thanks! I'm sorry in advance if this question is a repeat, but nothing else gives me any hints.

Answer 1

Have you tried setting the files in the same way as the docs? This specifies the source files slightly differently to how you have it:

less: {
  development: {
    options: {
      paths: ["assets/css"]
    },
    files: {
      "path/to/result.css": "path/to/source.less"
    }
  },
  production: {
    options: {
      paths: ["assets/css"],
      cleancss: true,
      modifyVars: {
        imgPath: '"http://mycdn.com/path/to/images"',
        bgColor: 'red'
      }
    },
    files: {
      "path/to/result.css": "path/to/source.less"
    }
  }
}

See the usage examples in the docs for more clarification: https://github.com/gruntjs/grunt-contrib-less#usage-examples