Fatal error: Cannot read property '1' of undefined

[isobar-ranesco]

I'm getting the above error when this tasks runs.. It will actually show the message underneath 'Building SVG sprites'.

Here is my setup:

    'svg-sprites': {
        'icons' : {
            options: {
                spriteElementPath: 'source/assets/svgs',
                spritePath: '.tmp/images/sprites/icons.svg',
                cssPath: '.tmp/styles/_icons.scss',
                sizes: {
                    std: 24,
                    small: 18,
                    large: 36
                },
                refSize: 'large',
                unit: 12
            }
        }