Using script tag sample code leads to an exception - works with older version of TFJS

[ToonTalk]

Using the sample code at https://github.com/tensorflow/tfjs-tsne#script-tag we get the following exception

tfjs-tsne:1 Uncaught TypeError: n.ENV.findBackend is not a function at F (tfjs-tsne:1) at new t (tfjs-tsne:1) at Object.t.tsne (tfjs-tsne:1) at tsne-test.html:7

However, changing it to load an older TFJS works fine

The following causes the exception