More robust get tags

taiga/projects/services/filters.py

@@ -21,14 +21,16 @@ from django.db import connection
 def _get_stories_tags(project):
     result = set()
     for tags in project.user_stories.values_list("tags", flat=True):
-        result.update(tags)
+        if tags:
+            result.update(tags)
     return result
 
 
 def _get_issues_tags(project):
     result = set()
     for tags in project.issues.values_list("tags", flat=True):
-        result.update(tags)
+        if tags:
+            result.update(tags)
     return result
 
 

taiga/projects/services/tags_colors.py

@@ -39,6 +39,9 @@ def remove_unused_tags(project):
 
 
 def update_project_tags_colors_handler(instance):
+    if instance.tags is None:
+        instance.tags = []
+
     for tag in instance.tags:
         defined_tags = map(lambda x: x[0], instance.project.tags_colors)
         if tag not in defined_tags: