Issue Description:

With the following code:

do {
    guard 1 == 2 else { break }
}

The compiler give the not-so-helpful error message:

error: 'break' is only allowed inside a loop, if, do, or switch

It would be much clearer to the user what the problem is and how to fix it, if it gave the same error message as it does in this case:

do {
    break
}

Which is:

error: unlabeled 'break' is only allowed inside a loop or switch, a labeled break is required to exit an if or do

The same problem occurs with if statements. For example, "if (true) { guard 1 == 2 else { break } }" gives the unhelpful message but "if (true) { break }" gives the helpful one.