Null value in error mvc.

Question

I want to click a viewDetails button and show user profile. But I have faced an issue.

 

it's me get code

public IActionResult UserDetail(int? UserId)-Here null userid
{
UserViewFullDetail obj_Detail = new UserViewFullDetail();
try
{
var Result = (from UM in _context.UserProfileMaster
join U in _context.UserMaster on UM.UserId equals U.UserId
where UM.UserId == U.UserId
where Convert.ToBoolean(UM.UserId == UserId)
select new
{
UM.UserImage,
UM.FirstName,
UM.MobileNumber,
UM.Country,
UM.UserId,
UM.ZipCode,
UM.InstaUserName,
UM.LevelBaseBall,
UM.Address,
U.Dob
}).FirstOrDefault();
if (Result != null)
{
obj_Detail.Name = Result.FirstName;
DateTime dt = Convert.ToDateTime(Result.Dob);
obj_Detail.DOB = string.Format("{0:dd MMMM yyyy}", dt);
var Mob = Result.MobileNumber;
obj_Detail.MobileNumber = String.Format("{0:##########}", double.Parse(Mob));
obj_Detail.Country = Result.Country;
obj_Detail.UserImage = Result.UserImage;
obj_Detail.InstaUserName = Result.InstaUserName;
obj_Detail.Address = Result.Address;
obj_Detail.LevelBaseBall = Result.LevelBaseBall;
it's me view code
@model NBP_BaseBallAdmin.ViewModel.UserViewFullDetail
@{
ViewData["Title"] = "UserDetail";
Layout = "~/Views/Shared/_Layout.cshtml";
}

<!-- Body Content Wrapper -->
<div class="ms-content-wrapper categories">
<div class="row">
<div class="col-md-12">
<nav aria-label="breadcrumb">
<div class="row">
<div class="col-md-6">
<ol class="breadcrumb pl-0">
<li class="breadcrumb-item"><a href="">User Management</a></li>
<li class="breadcrumb-item active" aria-current="page">User Detail</li>
</ol>
</div>
<div class="col-md-6">
<div class="invoice-buttons text-right">
<a href="#" class="btn btn-danger" data-toggle="modal" data-target="#warning-user">Report User</a>
</div>
</div>
</div>
</nav>
<div class="ms-panel">
<div class="ms-panel-header">
<div class="d-flex justify-content-between">
<div class="align-self-center align-left ">
<h6>User Details</h6>
</div>
<div class="col-md-6">
<div class="invoice-buttons text-right">
<a href="player-stats.html" class="btn btn-dark mr-2">View Stats</a>
<a href="update-user.html" class="btn btn-info">Update Profile</a>
</div>
</div>
</div>
</div>
<div class="ms-panel-body">
<div class="row">
<div class="col-lg-3">
<div class="master-img">
<img src=" @Html.DisplayFor(x => x.UserImage)" alt="doctor-img">
</div>
</div>
<div class="col-lg-9">
<div class="detail-sec">
<div class="d-flex align-item-center justify-content-between">
<h5 class="bold text-capitalize">William Rose</h5>
</div>
<ul class="Consultant-info">
@Html.HiddenFor(x => x.UserId)
<li><p>Instagram Username:</p> <span> @Html.DisplayFor(x => x.InstaUserName)</span></li>
<li><p>Date of Birth:</p> <span> @Html.DisplayFor(x => x.DOB)</span></li>
<li><p>Mobile no:</p><span> @Html.DisplayFor(x => x.MobileNumber) </span></li>
<li><p>Country:</p> <span> @Html.DisplayFor(x => x.Country)</span></li>
<li><p>Level of Baseball:</p> <span>@Html.DisplayFor(x => x.LevelBaseBall)</span></li>
<li><p>Zipcode:</p> <span>@Html.DisplayFor(x => x.ZipCode)</span></li>
<li><p>Address:</p><span>@Html.DisplayFor(x => x.ZipCode) </span></li>
</ul>
</div>
</div>
</div>
</div>
</div>

Please check this