Trying to create a node_type in DP 7
The error is complaining that it can't save the body field because you haven't specified the bundle of the object. But more importantly I think you want to look into the Entity API rather than creating a 'node_type'.

In drupal there are nodes and there are types of nodes called content types. To make it more abstract, nodes are entities of type 'node'.  Each content type is a 'bundle' of that entity type. Many things in drupal are entities, from users to comments to taxonomies.

If all you want to do is create a content type programatically, I think examples might have one. Otherwise just create the content type through configuration.