type ValidIndexSignatures = { a: { [index: string]: string; }; b: { [index: string]: string; }; }; interface I { [index: number]: string; [index: string]: string; } // See https://github.com/biomejs/biome/issues/175 const x: { [key: string]: string } = {}; let key; let a: { [key: string]: string }; let b: { [key: string]: string };