try fix

files/classes/comment.py

@@ -2,6 +2,7 @@ import time
 from math import floor
 from random import randint
 from urllib.parse import parse_qs, urlencode, urlparse
+from flask import g
 
 from sqlalchemy import Column, ForeignKey
 from sqlalchemy.dialects.postgresql import TSVECTOR

files/classes/submission.py

@@ -1,6 +1,7 @@
 import random
 import time
 from urllib.parse import urlparse
+from flask import g
 
 from sqlalchemy import Column, FetchedValue, ForeignKey
 from sqlalchemy.orm import deferred, relationship, scoped_session