Fix ByRef Nothing parameters

Author: mrmonday

ICSharpCode.CodeConverter/CSharp/NodesVisitor.cs

@@ -1474,7 +1474,7 @@ private bool NeedsVariableForArgument(VBSyntax.SimpleArgumentSyntax node)
                 bool isUsing = symbolInfo?.DeclaringSyntaxReferences.FirstOrDefault()?.GetSyntax()?.Parent?.Parent?.IsKind(VBasic.SyntaxKind.UsingStatement) == true;
 
                 var typeInfo = _semanticModel.GetTypeInfo(node.Expression);
-                bool isTypeMismatch = !typeInfo.Type.Equals(typeInfo.ConvertedType);
+                bool isTypeMismatch = typeInfo.Type == null || !typeInfo.Type.Equals(typeInfo.ConvertedType);
 
                 return (!isIdentifier && !isMemberAccess) || isProperty || isTypeMismatch || isUsing;
             }

Tests/CSharp/ExpressionTests.cs

@@ -230,6 +230,10 @@ ElseIf Bar(True = False) Then
         End If
     End Sub
 
+    Sub Foo5()
+        Bar(Nothing)
+    End Sub
+
     Sub Bar(ByRef b As Boolean)
     End Sub
 
@@ -290,6 +294,12 @@ public void Foo4()
         }
     }
 
+    public void Foo5()
+    {
+        var argb = default(bool);
+        Bar(ref argb);
+    }
+
     public void Bar(ref bool b)
     {
     }