CSS error 404-error

I already asked this question but did not get a real answer only where to look.

// Font Family Import
$font-family-import:    false;
@import url($font-family-import);

Where at mine it looks like

// Font Family Import / Google Fonts - Roboto
$font-family-import:                    'https://fonts.googleapis.com/css?family=Roboto';
@import url($font-family-import);

These are the errors

404 - file not found for file: styles/css/lib/false

404 - file not found for file: styles/css/custom/false