I faced the problem to which NullPointerException occurs when
Handler#getType() method is executed in ExprEditor#edit(Handler).
Originally, edit(Handler) should hook only catch block.
But, the method hooks the finally block and the synchronized block.

As the result of my own investigation, it turns out that the problem
is derived from the following specification of the Java class file.

1. The catch block, the finally block, and the synchronized block are stored
in the same exception table.

2. There is an area where the type of the exception (name of Exception class)
is stored in the entry of an exception table.

But, in the finally block and the synchronized block, 0 which means
arbitrary exceptions is stored.


The code of Handler#getType() is as follows.

public CtClass getType() throws NotFoundException {
 ConstPool cp = getConstPool();
 String name = cp.getClassInfo(etable.catchType(index));
 return Descriptor.toCtClass(name, thisClass.getClassPool());
}