This is contrary to what normally happens when you have try/finally without catch; in that case, it is rethrown automatically. That would be confusing if it was different, I think, and worthless if it was the same (being doing nothing).

Since

  try {
    ...
  } catch(err) {}

does that, is clear and explicit, and doesn’t make no-catch mean something different than it does in

  try {
    ...
  } finally {
    ...
  }

I think “no 'catch' as empty 'catch' when there is no 'finally'” is just unnecessary inconsistency for no meaningful gain.