Similar experience. Tried it once last week & it was exceptions all the way down. Dunno why Babili is attractive w/ battle-tested uglify still making big moves.
Re:UglifyJS 3 Released
by abritinthebay on Monday May 08, 2017 @11:14AM
(#14292211)
If you start a project with it it probably works fine (in that you can fix as you go).
I'm sure some people can get it to work but on anything vaguely complex it always errors out for me.
It's alpha software for a reason.