Private class field helpers throw a confusing error when in unbound method with undefined `this`

🔎 Search Terms

this undefined bind private identifier class __classPrivateFieldSet __classPrivateFieldGet bound unbound

🕗 Version & Regression Information

• This is the behavior in every version I tried

⏯ Playground Link

https://www.typescriptlang.org/play?#code/MYGwhgzhAEBiD29oG8BQ0PQMQDcwgFcBTaAXmgEYAmAZgBYBudTAcyIBcA1fYgCgEoU0AE4cCwgHbR2ACwCWEAHS4eRBtAC+qLamDwJEdtABmiMtAlEA7nEQCmu-RHggiikPBa8ABqfiK2LlUBcwASZD8Ajm5CIgENb34HAHpk6AB5eAAHCAAaaABJaAATOWKJAHIjACM5CWKAQkcDI0CY4nNIttUUtIAVGWF4KwgALmgAYTAJCXgjUTBi6CzhOTx2EgBbIk3qomETIc3oaeh4aoArImAjKxl4CBJQSBhSpdmjYuvwUWg5dmazlc7k8Pm6sRC5HC4L4-AS-FQQA

💻 Code

class Foo {
    #value = 1234;
    getValue() { return this.#value; }
}

const foo = new Foo();

console.log(`foo.getValue() = ${foo.getValue()}`);

// Oops, I didn't bind!
const getValue = foo.getValue;

// Throws: Cannot read private member from an object whose class did not declare it
console.log(`getValue() = ${getValue()}`)

🙁 Actual behavior

Throws Cannot read private member from an object whose class did not declare it.

But the actual problem is that this is undefined and I had no idea!

🙂 Expected behavior

A special error for this when undefined; IIRC there's no possible way this would normally pass, so a special error would be a lot more clear.

Additional information about the issue

No response

Beginne damit, den Zugriff auf ein ungebundenes privates Feld im verlinkten TypeScript Playground zu reproduzieren, und vergleiche ihn mit dem im Issue gezeigten gebundenen Aufruf. Verfolge, wie der vom Compiler generierte private-field-Helfer den Fehler meldet, ändere dann den undefined-this-Fall so, dass er den beschriebenen klareren Fehler erzeugt, und überprüfe beide Beispiele.