Nullish Coalescing Operator Returns a Syntax Error

[odog8]

The "nullish coalescing" operator is not defined. When attempting to use it, a syntax error is thrown.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Nullish_coalescing

[pvanb]

I get similar errors when using other ES6-only syntax, e.g. Optional Chaining. I wonder if JSConsole just doesn't support ES6? That would be unfortunate if true.