Playground is not supporting for "wrong order" classes

[xsetion]

Actual behavior:

I write two classes in the playground and when I run the code I get an error in the console which land on the extend function.

class Snake extends Greeter {
constructor() {
super();
}
skip(){}
}
class Greeter {
constructor() {}

skip(){
    console.log('nothig to skip');
    this.preEnd();
    console.log('so just ended');
}
preEnd(){}

}

Expected behavior:

The order of the class should not matter.

[jeffreymorlan]

Unlike functions, a class isn't actually created until its class declaration is reached, so it can't be forward referenced.

[DanielRosenwasser]

This is correct. Classes need to be declared before they are referenced on their value side.

[RyanCavanaugh]

This will now issue an error in cases where we can tell it's guaranteed not to work