Ripped out FlattenException into a separate extension method

src/Nancy/Helpers/ExceptionExtensions.cs

@@ -0,0 +1,32 @@
+namespace Nancy.Helpers
+{
+    using System;
+
+    internal static class ExceptionExtensions
+    {
+        internal static Exception FlattenInnerExceptions(this Exception exception)
+        {
+            var aggregateException = exception as AggregateException;
+            if (aggregateException != null)
+            {
+                var flattenedAggregateException = aggregateException.Flatten();
+
+                //If we have more than one exception in the AggregateException
+                //we have to send all exceptions back in order not to swallow any exceptions.
+                if (flattenedAggregateException.InnerExceptions.Count > 1)
+                {
+                    return flattenedAggregateException;
+                }
+
+                return flattenedAggregateException.InnerException.FlattenInnerExceptions();
+            }
+
+            if (exception != null && exception.InnerException != null)
+            {
+                return exception.InnerException.FlattenInnerExceptions();
+            }
+
+            return exception;
+        }
+    }
+}

src/Nancy/Nancy.csproj

@@ -173,6 +173,7 @@
     <Compile Include="Diagnostics\DefaultDiagnostics.cs" />
     <Compile Include="Diagnostics\DiagnosticsViewRenderer.cs" />
     <Compile Include="Helpers\CacheHelpers.cs" />
+    <Compile Include="Helpers\ExceptionExtensions.cs" />
     <Compile Include="IncludeInNancyAssemblyScanningAttribute.cs" />
     <Compile Include="IStaticContentProvider.cs" />
     <Compile Include="Json\Converters\TupleConverter.cs" />

src/Nancy/NancyEngine.cs

@@ -275,7 +275,7 @@ private Action<Task> HandleFaultedTask(NancyContext context, IPipelines pipeline
                 {
                     try
                     {
-                        var flattenedException = FlattenException(t.Exception);
+                        var flattenedException = t.Exception.FlattenInnerExceptions();
 
                         this.InvokeOnErrorHook(context, pipelines.OnError, flattenedException);
 
@@ -328,31 +328,5 @@ private void InvokeOnErrorHook(NancyContext context, ErrorPipeline pipeline, Exc
                 context.Items[ERROR_EXCEPTION] = e;
             }
         }
-
-        internal static Exception FlattenException(Exception exception)
-        {
-            if (exception is AggregateException)
-            {
-                var aggregateException = exception as AggregateException;
-
-                var flattenedAggregateException = aggregateException.Flatten();
-
-                //If we have more than one exception in the AggregateException
-                //we have to send all exceptions back in order not to swallow any exceptions.
-                if (flattenedAggregateException.InnerExceptions.Count > 1)
-                {
-                    return flattenedAggregateException;
-                }
-
-                return flattenedAggregateException.InnerException;
-            }
-
-            if (exception != null && exception.InnerException != null)
-            {
-                return FlattenException(exception.InnerException);
-            }
-
-            return exception;
-        }
     }
 }

src/Nancy/NancyEngineExtensions.cs

@@ -28,15 +28,16 @@ public static NancyContext HandleRequest(this INancyEngine nancyEngine, Request
         public static NancyContext HandleRequest(this INancyEngine nancyEngine, Request request, Func<NancyContext, NancyContext> preRequest)
         {
             var task = nancyEngine.HandleRequest(request, preRequest, CancellationToken.None);
+
             try
             {
                 task.Wait();
             }
             catch (Exception ex)
             {
-                var flattenedException = NancyEngine.FlattenException(ex);
-                throw flattenedException;
+                throw ex.FlattenInnerExceptions();
             }
+
             return task.Result;
         }
 

src/Nancy/Routing/DefaultRequestDispatcher.cs

@@ -137,7 +137,7 @@ private Response ResolveErrorResult(NancyContext context, Func<NancyContext, Exc
         {
             if (resolveResultOnError != null)
             {
-                var flattenedException = NancyEngine.FlattenException(exception);
+                var flattenedException = exception.FlattenInnerExceptions();
 
                 var result = resolveResultOnError.Invoke(context, flattenedException);
                 if (result != null)