for-of throws when followed by an empty block

import buble from 'buble';
buble.transform('for (let s of t) {}', { transforms: { dangerousForOf: true } });

will throw a TypeError

TypeError: Cannot read property 'start' of undefined
    at ForOfStatement.transpile (/node_modules/buble/dist/buble.umd.js:2021:38)
    at /node_modules/buble/dist/buble.umd.js:877:61
    at Array.forEach (native)

The following codes will not trigger this error.

for (let s of t);
for (let s in t) {};
for (let s of t) { s() };