Warning: Cannot read property 'js' of undefined

I stucked on this warning for a while. It happens if you set flow option with:

useminPrepare: {
    html: 'built/index.html',
    options: {
        root: '../../app/',
        dest: 'built',
        staging: 'tmp',
        flow: {
            steps: {'js': ['concat', 'uglifyjs']}
        }
    }
}

Fix is simple, just insert 'post' property:

useminPrepare: {
    html: 'built/index.html',
    options: {
        root: '../../app/',
        dest: 'built',
        staging: 'tmp',
        flow: {
            steps: {'js': ['concat', 'uglifyjs']},
            post: []
        }
    }
}

I think usage of steps parameter alone should be mentioned in readme or fixed.

thanks :+1:

It helps a lot

Had the same issue just now. Would be nice to not have to define a empty post flow.

Thanks, helped me too.

@calmdev @yfr which version of usemin are you using ?