GenBookBackend.contains(key) throws NPE if key not found

I think there is a bug in GenBookBackend.contains(Key).
The find method will return null if the key is not in the book
TreeNode node = find(key);
which means the next line will throw a NullPointerException
byte[] userData = node.getUserData();

Here is the whole method:
@Override
public boolean contains(Key key) {
checkActive();

try

{ DataPolice.setKey(key); TreeNode node = find(key); byte[] userData = node.getUserData(); // Some entries may be empty. return userData.length == 8; }

catch (IOException e)

{ return false; }

finally

{ DataPolice.setKey(null); }

}