Support discriminated union type or similar in database schemas about idb HOT 3 OPEN

interface DatabaseSchema extends DBSchema {
  posts: Record<string, Post>; // Like `list: { key: string; value: Post }`
  metadata: {
    times: { joined: string, lastSeen: string };
    counts: { posts: number; privateMessages: number }; 
  };
}

export type StoreValue<
  DBTypes extends DBSchema | unknown,
  StoreName extends StoreNames<DBTypes>,
  Key = any
> = DBTypes extends DBSchema
    ? (DBTypes[StoreName] & (Key extends StoreKey<DBTypes, StoreName> ? { key: Key } : {}))['value'] 
    : any;

get<
  Name extends StoreNames<DBTypes>,
  Key extends StoreKey<DBTypes, Name> | IDBKeyRange
>(
  storeName: Name,
  query: Key
): Promise<StoreValue<DBTypes, Name, Key> | undefined>;