Final answer:
The AttributeError occurs when trying to call the lower() method on a None object. To fix this, you need to check if the object is None before calling the method.
Step-by-step explanation:
The AttributeError: NoneType object has no attribute lower is a common error that occurs in programming when you try to call the lower() method on a None object. Python objects that have the lower() method are typically strings, and this method returns the lowercase version of the string. However, if the object is None, it does not have this method.
To fix this error, you need to ensure that the object you are calling the lower() method on is not None. You can use an if statement to check if the object is None before calling the method. Here is an example:
if object is not None:
object.lower()