There are a few cases where an empty statement, or absence of a statement can sneak in:

• for ( ; false ; ) has no initializer or update statement
• loop { continuing{ if (true) {break;} } } has no loop body statement

We need to add a row to the statement behaviours table, for the empty statement case.
And then in that case we can get rid of the rule about {} having behaviour of {Next} because we compose it from two other rules.