function getEventCallbacks () {
  return {
    async linkAccount ({ user, profile, account }) {
      if (account.provider === 'github') {
        await prisma.user.update({ where: { id: user.id }, data: { githubId: profile.name } })
      } else if (account.provider === 'twitter') {
        await prisma.user.update({ where: { id: user.id }, data: { twitterId: profile.name } })
      }
    },
    async signIn ({ user, profile, account, isNewUser }) {
      if (account.provider === 'github') {
        await prisma.user.update({ where: { id: user.id }, data: { githubId: profile.name } })
      } else if (account.provider === 'twitter') {
        await prisma.user.update({ where: { id: user.id }, data: { twitterId: profile.name } })
      }
    }
  }
}
Stores userIds in user table
@returns {Partial<import('next-auth').EventCallbacks>}