ReturnParameter fix for lambda_method (#11)

* ReturnParameter fix for lambda_method

* Bump version

src/Ben.Demystifier/Ben.Demystifier.csproj

@@ -9,7 +9,7 @@
     <RepositoryType>git</RepositoryType>
     <IncludeSymbols>true</IncludeSymbols>
     <IncludeSource>true</IncludeSource>
-    <Version>0.0.2</Version>
+    <Version>0.0.3</Version>
   </PropertyGroup>
 
   <PropertyGroup>

src/Ben.Demystifier/EnhancedStackTrace.Frames.cs

@@ -59,8 +59,8 @@ namespace System.Diagnostics
                     var fileName = frame.GetFileName();
                     var row = frame.GetFileLineNumber();
                     var column = frame.GetFileColumnNumber();
-
+                    var ilOffset = frame.GetILOffset();
-                    if (string.IsNullOrEmpty(fileName))
+                    if (string.IsNullOrEmpty(fileName) && ilOffset >= 0)
                     {
                         // .NET Framework and older versions of mono don't support portable PDBs
                         // so we read it manually to get file name and line information
@@ -167,9 +167,22 @@ namespace System.Diagnostics
             }
 
             if (method is System.Reflection.MethodInfo mi)
+            {
+                var returnParameter = mi.ReturnParameter;
+                if (returnParameter != null)
                 {
                     methodDisplayInfo.ReturnParameter = GetParameter(mi.ReturnParameter);
                 }
+                else if (mi.ReturnType != null)
+                {
+                    methodDisplayInfo.ReturnParameter = new ResolvedParameter
+                    {
+                        Prefix = "",
+                        Name = "",
+                        Type = TypeNameHelper.GetTypeDisplayName(mi.ReturnType, fullName: false, includeGenericParameterNames: true).ToString(),
+                    };
+                }
+            }
 
             if (method.IsGenericMethod)
             {

test/Ben.Demystifier.Test/DynamicCompilation.cs

@@ -0,0 +1,54 @@
+using System;
+using System.Diagnostics;
+using System.Linq.Expressions;
+using System.Text.RegularExpressions;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace Demystify
+{
+    public class DynamicCompilation
+    {
+        [Fact]
+        public async Task DoesNotPreventStackTrace()
+        {
+            // Arrange
+           var expression = Expression.Throw(
+                Expression.New(
+                    typeof(ArgumentException).GetConstructor(
+                        new Type[] {typeof(string)}),
+                    Expression.Constant( "Message")));
+
+            var lambda = Expression.Lambda<Action>(expression);
+
+            var action = lambda.Compile();
+
+            // Act
+            Exception demystifiedException = null;
+            try
+            {
+                await Task.Run(() => action()).ConfigureAwait(false);
+            }
+            catch(Exception ex)
+            {
+                demystifiedException = ex.Demystify();
+            }
+
+            // Assert
+            var stackTrace = demystifiedException.ToString();
+            stackTrace = ReplaceLineEndings.Replace(stackTrace, "");
+            var trace = stackTrace.Split(Environment.NewLine);
+
+            Assert.Equal(
+                new[] {
+                    "System.ArgumentException: Message",
+                    "   at void lambda_method(Closure)",
+                    "   at Task Demystify.DynamicCompilation.DoesNotPreventThrowStackTrace()+()=>{}",
+                    "   at void System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, object state)",
+                    "   at async Task Demystify.DynamicCompilation.DoesNotPreventThrowStackTrace()"}, 
+                trace);
+        }
+
+        private Regex ReplaceLineEndings = new Regex(" in [^\n\r]+");
+    }
+}