Cannot set headers after they are sent to the client

const authRouter = router({
    login: publicProcedure
        .input(UsersInsertSchema)
        .mutation(({ input, ctx }) => new AuthController().loginHandler(input, ctx)),
})

async loginHandler(data: typeof users.$inferInsert, ctx: Context) {
        const { accessToken, refreshToken } = await super.login(data)

        const cookies = new Cookies(ctx.req, ctx.res, {
            secure: process.env.NODE_ENV === 'production',
        })
        cookies.set('accessToken', accessToken, { ...accessTokenCookieOptions })
        cookies.set('refreshToken', refreshToken, {
            ...refreshTokenCookieOptions,
        })
        cookies.set('logged_in', 'true', { ...accessTokenCookieOptions })

        return { success: true }
    }

{
    "message": "Cannot set headers after they are sent to the client",
    "code": "ERR_HTTP_HEADERS_SENT"
}