Argument error in selectize.less causing compiler to abort

[urban]

The current version of selectize.js has a bug in the Less file. At approximately line 267 of serialize.less. You need to add a second set of parenthese to this line.

// change from 
margin-top: round(-1 * @selectize-arrow-size / 2);
// to
margin-top: round((-1 * @selectize-arrow-size / 2));