- int ystart = (int) (((SequenceNode) node.left()).ycount * chunk)
- + offy;
- int yend = (int) (((SequenceNode) node.right()).ycount * chunk)
+ int ystart = (node.left() == null ? 0
+ : (int) (((SequenceNode) node.left()).ycount * chunk)) + offy;
+ int yend = (node.right() == null ? 0
+ : (int) (((SequenceNode) node.right()).ycount * chunk))