Cannot insert the value NULL into column Name

This problem will arise when activating event handler/not sure about other feature.
The reason behind this is the commented code in the element.xml. After removing the commented code the feature will be activate sucessfully.

Using Objects in Event Receivers

Event receivers that instantiate SPSite, SPWeb, SPList, or SPListItem objects instead of using the instances passed via the event properties can cause the following problems:

They cause additional roundtrips to the database. (One write operation can result in up to five additional roundtrips in each event receiver.)


Calling the Update method on these instances can cause subsequent Update calls in other registered event receivers to fail.