Verification of Patch Request (The following request in image gave 500 error which can be prevented but do not)

I am not sure which Library is responsible for this issue and I am sorry if it is not related to this repo. I am trying to implement a Patch Request API using Asp.Net Core API 5.0 and so I have a parameter in my Controller Action which Takes `JsonPatchDocument`. As I tried it I noticed that we should have three stage of verification for this model including:
0- Validation of `JsonPatchDocument` according to Rest Standard (for example it should be an array! its element have standard shape including `op` and `path` and other constraints). This Validation should done after binding model and **it do not happen now**
1- Validation of `JsonPatchDocument` according to our Entity Type (For example does selected `path` existed in our entity)
2- Validation of Resulted `T` model from applying requested patch (for example field is email type and other verification attributes added to model `T`.

From the above list the validations 1 and 2 happens and is okay but validation 0 does not handle which I think it should be an step right after model binding. For example when sending the following patch request I get 500 status code error.
The action responsible for this code is as below:

`

[HttpPatch("{id}")]
public IActionResult PartiallyUpdateEmployee(Guid companyId, [FromRoute(Name = "id")] Guid employeeId, JsonPatchDocument input)
{
if (input == null)
{
_logger.LogError($"The Patch body is null for request {HttpContext.TraceIdentifier}");
return BadRequest("Patch reuest body is null");
}
if (ModelState.IsValid) // *******This is where Validation 0 should prevent the code from continuing and not**************
{
// check company is not null
var company = _repository.Company.GetById(companyId, false);
if (company == null)
{
_logger.LogInfo($"{HttpContext.TraceIdentifier}: the company with Id {companyId} does not exist in database");
return NotFound();
}

var employee = _repository.Employee.GetEmployee(companyId, employeeId, true);
if (employee == null)
{
_logger.LogInfo($"{HttpContext.TraceIdentifier}: the employee with Id {employeeId} for Company with Id {companyId} does not exist in database");
return NotFound();
}

var entityPart = _mapper.Map(employee);

// In the following we have two (plus one!) type of validation

input.ApplyTo(entityPart, ModelState); // Verification stage 1 which works as expected
TryValidateModel(entityPart); // Verification stage 2 which works as expected
// since Model State changed we should recheck it here
if (ModelState.IsValid)
{
_mapper.Map(entityPart, employee);
_repository.Save();
//return changed employee to user
var output = _mapper.Map(employee);
return Ok(output);
}

}
return BadRequest(ModelState);
}`
` `
I have added the following library for handling JsonPatchDocument
`Microsoft.AspNetCore.JsonPatch`
And I appreciate if checking the request against REST Standard for patch request done some where to prevent 500 status code error.
My Response
My logs:
and the related repository to test this:
https://github.com/CodeMazeBlog/httpclient-aspnetcore/tree/main/starter/CompanyEmployees