Cannot read property '$order' of undefined - Error Log

selectize.js/src/selectize.js

Line 1129 in 18ae944

optgroup = '';

selectize.js/src/selectize.js

Line 1133 in 18ae944

groups_order.push(optgroup);

When optgroup ='' and then it will be pushed to optgroups.
After that, the group_order sort by optgroups[i].$order which optgroups[''].$order will not exist.

selectize.js/src/selectize.js

Line 1143 in 18ae944

var b_order = self.optgroups[b].$order || 0;

Can we also check like below?

var a_order = self.optgroups[a] && self.optgroups[a].$order || 0;
var b_order = self.optgroups[b] && self.optgroups[b].$order || 0;

[risadams]

Good catch. A fix should be available in the next release