Safari fails on (async e => { if (void 0) return void await s.async.side.effect(); s.another.method(); })(); Described fully here https://github.com/mishoo/UglifyJS2/issues/2344
Also seems related to https://bugs.webkit.org/show_bug.cgi?id=176685
Is this still happening now that bug 176685 is fixed? You can get the newest build from <https://webkit.org/build-archives/> to test.
<rdar://problem/113884269>
*** This bug has been marked as a duplicate of bug 176685 ***