I encountered that this is not working if sub categories are added. Try the following block if you add sub categories.
if(!category) {
list.push(Discourse.ExternalNavItem.create({href: '/latest?solved=no', name: 'unresolved'}));
} else {
if(!category.parentCategory) {
list.push(Discourse.ExternalNavItem.create({href: '/c/'+category.slug+'?solved=no', name: 'unresolved'}));
} else {
list.push(Discourse.ExternalNavItem.create({href: '/c/'+category.parentCategory.slug+'/'+category.slug+'?solved=no', name: 'unresolved'}));
}
}
Cheers