Mixed-in classes with functions returning 'this' have TS2526 error in DTS file

Bug Report

🔎 Search Terms

TS2526 mixin declaration this

🕗 Version & Regression Information

• This is the behavior in every version I tried

⏯ Playground Link

Playground link

💻 Code

class Sprite {
  name = "";
 
  constructor(name: string) {
    this.name = name;
  }
}

type Constructor = new (...args: any[]) => {};
 
function Scale<TBase extends Constructor>(Base: TBase) {
  return class Scaling extends Base {
    _scale = 1;
 
    setScale(scale: number): this {
      this._scale = scale;
      return this;
    }
  };
}

export const A = Scale(Sprite);

DTS:

declare class Sprite {
    name: string;
    constructor(name: string);
}
export declare const A: {
    new (...args: any[]): {
        _scale: number;
// A 'this' type is available only in a non-static member of a class or interface.ts(2526)
        setScale(scale: number): this;
    };
} & typeof Sprite;
export {};

🙁 Actual behavior

TS2526 error appears in emitted dts file

🙂 Expected behavior

No error (TS files that have no errors should not emit DTS file with errors)

Start with the linked TypeScript Playground reproduction and compare the valid TS source with its emitted DTS output. Trace declaration emission for the mixed-in class and its setScale method. Done means the reproduced source emits a DTS file without the TS2526 error.