How to fix "x is not a function" error on AOT

Question

I am running Angular AOT using 3rd party library (tether.js) for ng-lightning. JIT works fine, but after building it with AOT & Rollup, I get the following error (tether.js):

Uncaught TypeError: S is not a function

I have the following definition inside System.config.js:

map: {  'tether': 'npm:tether/dist/js' }

and inside packages:

packages: {  'tether': { defaultExtension: 'js' } }

Is there a better way to import so I won't get this error?