feat: warn user if whitelisted tags are less than minTags

public/language/en-GB/admin/manage/categories.json

@@ -76,6 +76,7 @@
 	"alert.user-search": "Search for a user here...",
 	"alert.find-group": "Find a Group",
 	"alert.group-search": "Search for a group here...",
+	"alert.not-enough-whitelisted-tags": "Whitelisted tags are less than minimum tags, you need to create more whitelisted tags!",
 	"collapse-all": "Collapse All",
 	"expand-all": "Expand All",
 	"disable-on-create": "Disable on create"

public/src/admin/manage/category.js

@@ -48,6 +48,11 @@ define('admin/manage/category', [
 		$('[data-name="bgColor"], [data-name="color"]').each(enableColorPicker);
 
 		$('#save').on('click', function () {
+			var tags = $('#tag-whitelist').val() ? $('#tag-whitelist').val().split(',') : [];
+			if (tags.length && tags.length < parseInt($('#cid-min-tags').val(), 10)) {
+				return app.alertError('[[admin/manage/categories:alert.not-enough-whitelisted-tags]]');
+			}
+
 			if (Object.keys(modified_categories).length) {
 				socket.emit('admin.categories.update', modified_categories, function (err, result) {
 					if (err) {