Don't try to set password if it isn't passed in

{{cookiecutter.repo_name}}/{{cookiecutter.repo_name}}/models.py

@@ -19,6 +19,7 @@ class User(db.Model):
     def __init__(self, username=None, email=None, password=None):
         self.username = username
         self.email = email
+        if password:
             self.set_password(password)
 
     def set_password(self, password):