with the new @Nullable checking. Real live, dump-an-NPE-stack-trace bugs. Worse, bugs that would only occur under obscure circumstances (usually in mid-edit when the parse tree is in an inconsistent state) that there was no way in hell I would find in testing. In short, that's fifty exception stack trace e-mails that won't be showing up in my inbox. And the PSI doesn't even look to be fully annotated yet!
May I humbly suggest to JetBrains marketing that this is a major differentiating feature, and should be trumpetted as such.