Fix: On new clients, trying to get Client.by_code(None) would raise an error

brewman/models/auth.py

@@ -45,6 +45,8 @@ class Client(Base):
 
     @classmethod
     def by_code(cls, code):
+        if code is None:
+            return None
         if not isinstance(code, int):
             code = int(code)
         return DBSession.query(cls).filter(cls.code == code).first()