vis.js is not compatible with YUI Compressor due to use of reserved words

Trying to use vis Timeline in a Sencha ExtJS application. The Sencha Cmd build tool uses YUI Compressor by default. It barfs on vis.js due to use of reserved words, e.g. "default" in the following:

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

PS. I also tried using the Closure Compiler and this failed for some other reason (can't recall the details).