As posted on the list :

The attached patch fixes the problem.
For some reason, when the method is a generator (contains yield
statements), the 'local' used as the exception handler is not visited
and thus does not have a LocalBuilder handy.

I'm not commiting it yet since it is more a workaround hack than a
solution to the actual problem (the node not being visited), but well
have not much time to do it now and debugging a visitor pattern by
omission (code not run) is quite time-consuming :s

Marking it blocker just so not to forget to check in above patch if the issue is still not properly fixed in time for 0.9 release.

GeneratorMethodProcessor transforms every local variable into a field of the IEnumerator implementation. This is clearly wrong for exception variables because their scope never outlives a single method invocation.

Fixed in rev. 3101.