From 532e7ad451ce10d74d6f88e8e0f538567394666d Mon Sep 17 00:00:00 2001
From: Cotes Chung <11371340+cotes2020@users.noreply.github.com>
Date: Fri, 22 May 2020 18:02:28 +0800
Subject: [PATCH] Fixed a bug in the Categories hierarchy. (#48, #57)

When one post have only one category will hit the bug.
---
 tabs/categories.md | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/tabs/categories.md b/tabs/categories.md
index 504a2fe..a224ae7 100644
--- a/tabs/categories.md
+++ b/tabs/categories.md
@@ -20,9 +20,11 @@ title: Categories
 
     {% for post in posts_of_category %}
       {% assign second_category = post.categories[1] %}
-      {% unless sub_categories contains second_category %}
-        {% assign sub_categories = sub_categories | push: second_category %}
-      {% endunless %}
+      {% if second_category %}
+        {% unless sub_categories contains second_category %}
+          {% assign sub_categories = sub_categories | push: second_category %}
+        {% endunless %}
+      {% endif %}
     {% endfor %}
 
     {% assign sub_categories = sub_categories | sort %}