AttributeError: 'NoneType' object has no attribute 'data'

This error message typically occurs when you try to access an attribute of a NoneType object, which means that the object does not have any value or data assigned to it.

For example, if you have a variable that is assigned None and you try to access its data attribute, you will get this error message:

my_var = None
print(my_var.data) # AttributeError: 'NoneType' object has no attribute 'data'

To fix this error, you need to make sure that the object you are trying to access has a value assigned to it. You can do this by checking if the object is None before trying to access its attributes:

my_var = None
if my_var is not None:
    print(my_var.data)
else:
    print("my_var is None")

Alternatively, you can initialize the object with a default value so that it always has a value assigned to it:

my_var = MyObject()
print(my_var.data) # assuming MyObject() initializes the 'data' attribute