Fixes #52 - NRE for arbitrary expressions in With Block

Flip the conditional to target the elvis expression instead which is the more specific case. Basically any statement can appear inside a with block
Also catch an obvious case of a missing argument list - would be good to look for more subtle ones of these

ICSharpCode.CodeConverter/CSharp/NodesVisitor.cs

@@ -853,10 +853,9 @@ namespace ICSharpCode.CodeConverter.CSharp
 
                 var left = (ExpressionSyntax)node.Expression?.Accept(TriviaConvertingVisitor);
                 if (left == null) {
-                    if (!node.Parent.Parent.IsKind(VBasic.SyntaxKind.WithBlock)) {
+                    if (IsSubPartOfConditionalAccess(node)) {
                         return SyntaxFactory.MemberBindingExpression(simpleNameSyntax);
                     }
-
                     left = SyntaxFactory.IdentifierName(withBlockTempVariableNames.Peek());
                 }
 
@@ -873,9 +872,23 @@ namespace ICSharpCode.CodeConverter.CSharp
                 return memberAccessExpressionSyntax;
             }
 
+            private static bool IsSubPartOfConditionalAccess(VBSyntax.MemberAccessExpressionSyntax node)
+            {
+                var firstPossiblyConditionalAncestor = node.Parent;
+                while (firstPossiblyConditionalAncestor != null &&
+                       firstPossiblyConditionalAncestor.IsKind(VBasic.SyntaxKind.InvocationExpression,
+                           VBasic.SyntaxKind.SimpleMemberAccessExpression))
+                {
+                    firstPossiblyConditionalAncestor = firstPossiblyConditionalAncestor.Parent;
+                }
+
+                return firstPossiblyConditionalAncestor?.IsKind(VBasic.SyntaxKind.ConditionalAccessExpression) == true;
+            }
+
             public override CSharpSyntaxNode VisitConditionalAccessExpression(VBSyntax.ConditionalAccessExpressionSyntax node)
             {
-                return SyntaxFactory.ConditionalAccessExpression((ExpressionSyntax)node.Expression.Accept(TriviaConvertingVisitor), (ExpressionSyntax)node.WhenNotNull.Accept(TriviaConvertingVisitor));
+                var leftExpression = (ExpressionSyntax)node.Expression?.Accept(TriviaConvertingVisitor) ?? SyntaxFactory.IdentifierName(withBlockTempVariableNames.Peek());
+                return SyntaxFactory.ConditionalAccessExpression(leftExpression, (ExpressionSyntax)node.WhenNotNull.Accept(TriviaConvertingVisitor));
             }
 
             public override CSharpSyntaxNode VisitArgumentList(VBSyntax.ArgumentListSyntax node)
@@ -1290,7 +1303,7 @@ namespace ICSharpCode.CodeConverter.CSharp
 
                 return SyntaxFactory.InvocationExpression(
                     (ExpressionSyntax)node.Expression.Accept(TriviaConvertingVisitor),
-                    (ArgumentListSyntax)node.ArgumentList.Accept(TriviaConvertingVisitor)
+                    (ArgumentListSyntax)node.ArgumentList?.Accept(TriviaConvertingVisitor) ?? SyntaxFactory.ArgumentList()
                 );
             }
 

Tests/CSharp/StatementTests.cs

@@ -243,7 +243,7 @@ class TestClass
     Private Sub TestMethod()
         With New System.Text.StringBuilder
             .Capacity = 20
-            .Length = 0
+            ?.Length = 0
         End With
     End Sub
 End Class", @"using System;
@@ -258,7 +258,39 @@ class TestClass
         {
             var withBlock = new System.Text.StringBuilder();
             withBlock.Capacity = 20;
-            withBlock.Length = 0;
+            withBlock?.Length = 0;
+        }
+    }
+}");
+        }
+
+        [Fact]
+        public void WithBlock2()
+        {
+            TestConversionVisualBasicToCSharpWithoutComments(@"Class TestClass
+    Private Sub Save()
+        Using cmd As SqlCommand = new SqlCommand()
+            With cmd
+            .ExecuteNonQuery()
+            ?.ExecuteNonQuery()
+            .ExecuteNonQuery
+            ?.ExecuteNonQuery
+            End With
+        End Using
+    End Sub
+End Class", @"class TestClass
+{
+    private void Save()
+    {
+        using (SqlCommand cmd = new SqlCommand())
+        {
+            {
+                var withBlock = cmd;
+                withBlock.ExecuteNonQuery();
+                withBlock?.ExecuteNonQuery();
+                withBlock.ExecuteNonQuery();
+                withBlock?.ExecuteNonQuery();
+            }
         }
     }
 }");