Unable to extend Error when targeting es5 with TS 2.1

[asvetliakov]

TypeScript Version: 2.1.0-dev.20161104

Code
tsconfig.json

{                       
  "compilerOptions": {  
    "target": "es5",    
    "module": "commonjs"
  }      
}                       

// A *self-contained* demonstration of the problem follows...
class Test extends Error {
        constructor(message: string) {
                super(message);
        }
}

const test = new Test("test");

console.log(`Instance of error: ${test instanceof Error}`);
console.log(`Instance of test: ${test instanceof Test}`);

Expected behavior:

Instance of error: true
Instance of test: true

Actual behavior:

Instance of error: true
Instance of test: false

It works with TS 2.0.7

[aluanhaddad]

For reference, this affects all code that extends a function that is both callable constructable. For example, see #11919. Since Error(msg) is a factory, its return value is propagated through the super call and used instead of this.

[asvetliakov]

I won't complain if it's intentional change (workaround-ed easily), but at least it should be documented (i.e. breaking change) or even better the TS compiler should give error on es5 target when 2.1 will be released.

[aluanhaddad]

@asvetliakov I agree. I don't know what the intent exactly is. Either way subclassing builtins like Array and Error is broken. An error should be issued.

[DanielRosenwasser]

It actually is an intentional change and documented here. I apologize about the inconvenience.

[DanielRosenwasser]

Marking as a duplicate of #12123.