Union in a computed property allows any assignment to property value #38663

type Key = 'a' | 'b';

const index1: Record<Key, string> = { a: '', b: 0 }; // Errors as expected, ok
const index2: Record<Key, string> = { a: '', b: '' };

const b: Key = 'b';

const index3: Record<Key, string> = { ...index2, [b]: 0 }; // Errors as expected, ok

declare var k: Key;

// No errors, allowing anything to be assigned to string
const index4: Record<Key, string> = { ...index2, [k]: [] };
const index5: Record<Key, string> = { a: '', b: '', [k]: 0 };