Invalid form key returns internal server error

When sending a request with content type `application/x-www-form-urlencoded` and a malformed key in the request body (e.g. `[spc=123`) ASP NET Core throws an Internal Server Error with the following stack trace:

```
fail: Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware[1]
An unhandled exception has occurred while executing the request.
System.ArgumentException: The key '[spc' is invalid JQuery syntax because it is missing a closing bracket. (Parameter 'key')
at Microsoft.AspNetCore.Mvc.ModelBinding.JQueryKeyValuePairNormalizer.NormalizeJQueryToMvc(StringBuilder builder, String key)
at Microsoft.AspNetCore.Mvc.ModelBinding.JQueryKeyValuePairNormalizer.GetValues(IEnumerable`1 originalValues, Int32 valueCount)
at Microsoft.AspNetCore.Mvc.ModelBinding.JQueryFormValueProviderFactory.AddValueProviderAsync(ValueProviderFactoryContext context)
at Microsoft.AspNetCore.Mvc.ModelBinding.CompositeValueProvider.CreateAsync(ActionContext actionContext, IList`1 factories)
at Microsoft.AspNetCore.Mvc.ModelBinding.CompositeValueProvider.TryCreateAsync(ActionContext actionContext, IList`1 factories)
at Microsoft.AspNetCore.Mvc.Controllers.ControllerBinderDelegateProvider.<>c__DisplayClass0_0.<g__Bind|0>d.MoveNext()
--- End of stack trace from previous location ---
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.g__Awaited|13_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|20_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Logged|17_1(ResourceInvoker invoker) at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Logged|17_1(ResourceInvoker invoker) at Microsoft.AspNetCore.Routing.EndpointMiddleware.g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
at Swashbuckle.AspNetCore.SwaggerUI.SwaggerUIMiddleware.Invoke(HttpContext httpContext)
at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)
at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)
```

Bad user input should return a Bad Request response instead.

## Repro steps

* Create a new ASP.NET Core Web API project (.NET 6) using the project template
* Modify the `WeatherForecastController` to Get method to:
```
[HttpPost(Name = "GetWeatherForecast")]
public IEnumerable Get([FromForm] string spc)
{
return Enumerable.Range(1, 5).Select(index => new WeatherForecast
{
Date = DateTime.Now.AddDays(index),
TemperatureC = Random.Shared.Next(-20, 55),
Summary = Summaries[Random.Shared.Next(Summaries.Length)]
})
.ToArray();
}
```
* Send the following HTTP request:
```
POST https://localhost:7040/WeatherForecast HTTP/1.1
User-Agent: Fiddler
Content-Type: application/x-www-form-urlencoded
Host: localhost:7040
Content-Length: 8

[spc=123
```