jekyll-import: improve tags handler

shared/jekyll_import.py

@@ -438,7 +438,7 @@ class JekyllArticleImporter:
         for gallery in meta["fancybox"]:
             # gallery by měl být dict s name a img
             gallery_name = gallery.get("name", "")
-            gallery_images = gallery.get("img", [])
+            gallery_images = gallery.get("img", []) or []
 
             if not len(gallery_images):
                 self.page_log += (
@@ -516,7 +516,12 @@ class JekyllArticleImporter:
         return meta_dict
 
     def handle_tags(self, article, meta):
-        for tag_name in meta.get("tags", []):
+        tags = meta.get("tags", []) or []  # někdy jsou tags None
+
+        if type(tags) == str:  # někdy jsou tags str
+            tags = [tags]
+
+        for tag_name in tags:
             try:
                 article.tags.add(tag_name)
             except ValueError: