NullReferenceException when posting (razor pages)

<div>

I have a small application for arranging events, and wants have a page for sending emails or sms to all participants. Have this code behind:

    public class MessagingModel : PageModel
    {
        private readonly IMessageLogService  _messageLogService;
        private readonly IEventInfoService _eventinfos;
        private readonly IRegistrationService _registrationService;
        private readonly RegistrationEmailSender _registrationEmailSender;

        [BindProperty]
        public InputModel Input { get; set; }

        [TempData]
        public string StatusMessage { get; set; }

        public class InputModel
        {
            public string EmailSubject {get; set;}
            public string EmailContent { get; set; }
            public string SmsContent { get; set; }
        }

        public MessagingModel(
            IMessageLogService messageLogService, 
            IEventInfoService eventinfos, 
            IRegistrationService registrationService,
            RegistrationEmailSender registrationEmailSender)
        {
            _messageLogService = messageLogService;
            _eventinfos = eventinfos;
            _registrationService = registrationService;
            _registrationEmailSender = registrationEmailSender;
        }

        public EventInfo EventInfo {get;set;}

        public async Task<IActionResult> OnGetAsync(int id)
        {
            EventInfo = await _eventinfos.GetAsync(id);
            return Page();
        }

        public async Task<IActionResult> OnPostSendEmailAsync(int id) {
            if (!ModelState.IsValid)
            {
                return Page();
            }
            // Send emails

            StatusMessage = "Email sent";
            EventInfo = await _eventinfos.GetAsync(id);
            return RedirectToPage();
        }

        public async Task<IActionResult> OnPostSendSMSAsync(int id) {
            if (!ModelState.IsValid)
            {
                return Page();
            }
            // Send SMS

            StatusMessage = "SMS sent";
            EventInfo = await _eventinfos.GetAsync(id);
            return RedirectToPage();
        }

        }
    }

</div> <div>However I get: </div> <div>

NullReferenceException: Object reference not set to an instance of an object.
losol.EventManagement.Pages.Admin.Events.Messaging_Page+<ExecuteAsync>d__20.MoveNext() in Messaging.cshtml+
    ViewData["Title"] = "Meldinger – " + @Model.EventInfo.Title;

So it seems that the EventInfo is not loaded after posting the page. How do I fix it?</div>