Fiddle to reproduce: https://jsfiddle.net/9etuLmj6/4

Upon having grouped options, where one of them is disabled and the option group-select is set to false (or not passed down as a prop), the option that should be disabled gets the extra class multiselect__option--group while it is clearly not a group.

Removing $isDisabled: true from the option or settings :group-select="true" on the multiselect will not set this class.

In the above example this can be seen because the option 'Adonis' is red or by inspecting the html.

This wouldn't really be a problem, until we want to apply custom css to option group headers.