The default startPath argument acts wierd. You can't add new points without breaking it in Firefox.

Tested with mojs 1.0.3 and mojs-curve-editor 1.7.1 using Firefox 88 (works in Chrome)

The startPath defined here:

M0,100 L100,0

Codepen: https://codepen.io/sandstedt/pen/RwKXRjV?editors=1010