SignalArray is not subclassable

[justinfagnani]

Subclassing SignalArray doesn't work even when there are no build errors.

Example:

import {SignalArray} from 'signal-utils/array';

class MyArray<T> extends SignalArray<T> {  
  sayHello() {
    return 'Hello';
  }
}

const a = new MyArray(['a', 'b', 'c']);
console.log(a.constructor.name);
console.log(a.sayHello());

This logs:

Array

Then throws Uncaught TypeError: a.sayHello is not a function

[NullVoxPopuli]

This was never a design goal of the implementation.

Resolving it probably depends on whatever the answer is to your other issue:

• Benchmarks to back performance claims about proxies vs subclasses #95