iTunes crashes when I press refresh on the podcast pane
It looks like after the last iTunes update a second empty Podcast item appeared on the left side column. The original Podcast pane started crashing as described on the original question.

I've delete the original Podcast item from the left column (it seems the application treated it as a sort of legacy playlist). And re-subscribed manually to all my podcasts (the new subscriptions get to appear in the new item).

After some frustration, it all seems to work again now.