update a non-existent field in instance when updating this instance

[beaulian]

Hi,

According to the following code, when we update an instance, whatever we define other fields (not in the Model) in the Schema, these fields will be inserted to the instance, is it a bug?

https://github.com/marshmallow-code/marshmallow-sqlalchemy/blob/d4c7479b15a00abc76011b76a6b22db2386d23e1/src/marshmallow_sqlalchemy/load_instance_mixin.py#L73-L76

Thanks

[lafrech]

I would say it is a bug in client code.

Should this lib actively try to catch this?