Fix issue with concurrent logging (#63)

* Fix issue with concurrent logging

* Fix namespace + code format/cleanup

src/WireMock.Net/Owin/AspNetCoreSelfHost.cs

@@ -46,6 +46,7 @@ namespace WireMock.Owin
             _host = new WebHostBuilder()
                 .Configure(appBuilder =>
                 {
+                    appBuilder.UseMiddleware<GlobalExceptionMiddleware>();
                     _options.PreWireMockMiddlewareInit?.Invoke(appBuilder);
                     appBuilder.UseMiddleware<WireMockMiddleware>(_options);
                     _options.PostWireMockMiddlewareInit?.Invoke(appBuilder);

src/WireMock.Net/Owin/GlobalExceptionMiddleware.cs

@@ -0,0 +1,49 @@
+using System;
+using System.Threading.Tasks;
+using Newtonsoft.Json;
+#if !NETSTANDARD
+using Microsoft.Owin;
+#else
+using Microsoft.AspNetCore.Http;
+#endif
+
+namespace WireMock.Owin
+{
+#if !NETSTANDARD
+    internal class GlobalExceptionMiddleware : OwinMiddleware
+#else
+    internal class GlobalExceptionMiddleware
+#endif
+    {
+#if !NETSTANDARD
+        public GlobalExceptionMiddleware(OwinMiddleware next) : base(next) { }
+#else
+        public GlobalExceptionMiddleware(RequestDelegate next)
+        {
+            Next = next;
+        }
+#endif
+
+#if NETSTANDARD
+    public RequestDelegate Next { get; private set; }
+#endif
+
+    private readonly OwinResponseMapper _responseMapper = new OwinResponseMapper();
+
+#if !NETSTANDARD
+        public override async Task Invoke(IOwinContext ctx)
+#else
+        public async Task Invoke(HttpContext ctx)
+#endif
+        {
+            try
+            {
+                await Next?.Invoke(ctx);
+            }
+            catch (Exception ex)
+            {
+                await _responseMapper.MapAsync(new ResponseMessage { StatusCode = 500, Body = JsonConvert.SerializeObject(ex) }, ctx.Response);
+            }
+        }
+    }
+}

src/WireMock.Net/Owin/OwinSelfHost.cs

@@ -61,6 +61,7 @@ namespace WireMock.Owin
 
             Action<IAppBuilder> startup = app =>
             {
+                app.Use<GlobalExceptionMiddleware>();
                 _options.PreWireMockMiddlewareInit?.Invoke(app);
                 app.Use<WireMockMiddleware>(_options);
                 _options.PostWireMockMiddlewareInit?.Invoke(app);

src/WireMock.Net/Owin/WireMockMiddleware.cs

@@ -5,6 +5,7 @@ using WireMock.Matchers.Request;
 using System.Linq;
 using WireMock.Matchers;
 using WireMock.Util;
+using Newtonsoft.Json;
 #if !NETSTANDARD
 using Microsoft.Owin;
 #else
@@ -124,7 +125,7 @@ namespace WireMock.Owin
             }
             catch (Exception ex)
             {
-                response = new ResponseMessage { StatusCode = 500, Body = ex.ToString() };
+                response = new ResponseMessage { StatusCode = 500, Body = JsonConvert.SerializeObject(ex) };
             }
             finally
             {

src/WireMock.Net/Owin/WireMockMiddlewareOptions.cs

@@ -4,6 +4,7 @@ using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using WireMock.Logging;
 using WireMock.Matchers;
+using WireMock.Util;
 #if !NETSTANDARD
 using Owin;
 #else
@@ -22,7 +23,7 @@ namespace WireMock.Owin
 
         public IList<Mapping> Mappings { get; set; } = new List<Mapping>();
 
-        public ObservableCollection<LogEntry> LogEntries { get; } = new ObservableCollection<LogEntry>();
+        public ObservableCollection<LogEntry> LogEntries { get; } = new ConcurentObservableCollection<LogEntry>();
 
         public int? RequestLogExpirationDuration { get; set; }