closes #2409

src/categories.js

@@ -168,6 +168,7 @@ var async = require('async'),
 		category.name = validator.escape(category.name);
 		category.disabled = parseInt(category.disabled, 10) === 1;
 		category.icon = category.icon || 'hidden';
+		category.post_count = category.post_count || 0;
 
 		if (category.description) {
 			category.description = validator.escape(category.description);

src/controllers/categories.js

@@ -142,7 +142,7 @@ categoriesController.get = function(req, res, next) {
 			var topicIndex = utils.isNumber(req.params.topic_index) ? parseInt(req.params.topic_index, 10) - 1 : 0;
 			var topicCount = parseInt(results.categoryData.topic_count, 10);
 
-			if (topicIndex < 0 || topicIndex > topicCount - 1) {
+			if (topicIndex < 0 || topicIndex > Math.max(topicCount - 1, 0)) {
 				var url = '/category/' + cid + '/' + req.params.slug + (topicIndex > topicCount ? '/' + topicCount : '');
 				return res.locals.isAPI ? res.status(302).json(url) : res.redirect(url);
 			}