Fix null dereference in ValidateAuthenticationStatus

[huncrys]

The example config doesn't pass X-PlexSSO-Original-URI for the auth request, so serviceUri will be null. With the applied fix, it works for me.

plexsso  |       An unhandled exception has occurred while executing the request.
plexsso  |       System.NullReferenceException: Object reference not set to an instance of an object.
plexsso  |          at PlexSSO.Service.Auth.AuthenticationValidator.ValidateAuthenticationStatus(Identity identity, ServiceName serviceName, ServiceUri serviceUri)
plexsso  |          at PlexSSO.Controllers.SsoController.Get()
plexsso  |          at lambda_method1(Closure, Object, Object[])
plexsso  |          at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.SyncObjectResultExecutor.Execute(ActionContext actionContext, IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
plexsso  |          at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeActionMethodAsync()
plexsso  |          at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
plexsso  |          at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeNextActionFilterAsync()
plexsso  |       --- End of stack trace from previous location ---
plexsso  |          at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Rethrow(ActionExecutedContextSealed context)
plexsso  |          at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
plexsso  |          at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeInnerFilterAsync()
plexsso  |       --- End of stack trace from previous location ---
plexsso  |          at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|25_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
plexsso  |          at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
plexsso  |          at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
plexsso  |          at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeFilterPipelineAsync()
plexsso  |       --- End of stack trace from previous location ---
plexsso  |          at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
plexsso  |          at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
plexsso  |          at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
plexsso  |          at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
plexsso  |          at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddlewareImpl.<Invoke>g__Awaited|10_0(ExceptionHandlerMiddlewareImpl middleware, HttpContext context, Task task)```

[drkno]

Oops that’s an embarrassing bug.