index.js

let user = await context.prisma.query.user(
  {
    where: {
      email: args.login,
    },
  },
);

if (!user) {
  user = await context.prisma.query.user(
    {
      where: {
        nickname: args.login,
      },
    },
  );

  if (!user) {
    throw new Error(`No such user found`);
  }
}

// const user = await context.prisma.query.user(
//   {
//     where: {
//       OR: [
//         { email: args.login, },
//         { nickname: args.login },
//       ],
//     },
//   },
// );