Fixed a bug in the Categories hierarchy. (cotes2020#48, cotes2020#57)

cotes2020 · cotes2020 · commit 090c37249e84 · 2020-05-22T18:06:40.000+08:00
When one post have only one category will hit the bug.
diff --git 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 %}
