Should this be valid code?

[leobalter]

new new class {}()?.constructor?.(); (equivalent to new new class {}().constructor();)

When reading the proposed syntax grammar, this seems correct, but it's one of the few errors I found when parsing with Babel.

Is that an error from Babel or the actual code?

[claudepache]

new new class {}()?.constructor?.(); is equivalent to new FOO?.constructor?.(), which should be a syntax error. Indeed, we don’t support “optional new”, my main reason being that the expected complication of the grammar largely outweighs the (lack of) use cases. See #22.

[claudepache]

Closing per housekeeping.