If I write the following code:

class C {
    constructor(private ...x) {
    }
}

then I get the error ',' expected..

Instead, I should get an error like A parameter property cannot be declared using a rest parameter.

As motivation, for the following

class C {
    constructor(private {x}) {
    }
}

we currently give the error A parameter property may not be a binding pattern.

Additionally, in fixing this, the two should be consistent. Preferably, the new error for the latter should be A parameter property may not be declared using a binding pattern.