refactor: updated some syntax to use latest c# features

Author: amyskippy

MapDataReader/MapperGenerator.cs

@@ -169,20 +169,20 @@ internal class TargetTypeTracker : ISyntaxContextReceiver
 
 		public void OnVisitSyntaxNode(GeneratorSyntaxContext context)
 		{
-			if (context.Node is ClassDeclarationSyntax cdecl)
-				if (cdecl.IsDecoratedWithAttribute("GenerateDataReaderMapper"))
-					TypesNeedingGening = TypesNeedingGening.Add(cdecl);
+			if (context.Node is not ClassDeclarationSyntax classDec) return;
+			
+			if (classDec.IsDecoratedWithAttribute("GenerateDataReaderMapper"))
+				TypesNeedingGening = TypesNeedingGening.Add(classDec);
 		}
 	}
 
 	internal static class Helpers
 	{
-		internal static bool IsDecoratedWithAttribute(this TypeDeclarationSyntax cdecl, string attributeName) =>
-			cdecl.AttributeLists
+		internal static bool IsDecoratedWithAttribute(this TypeDeclarationSyntax typeDec, string attributeName) =>
+			typeDec.AttributeLists
 				.SelectMany(x => x.Attributes)
 				.Any(x => x.Name.ToString().Contains(attributeName));
 
-
 		internal static string FullName(this ITypeSymbol typeSymbol) => typeSymbol.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat);
 
 		internal static string StringConcat(this IEnumerable<string> source, string separator) => string.Join(separator, source);
@@ -214,12 +214,11 @@ internal static bool IsNullableEnum(this ITypeSymbol symbol)
 			//tries to get underlying non-nullable type from nullable type
 			//and then check if it's Enum
 			if (symbol.NullableAnnotation == NullableAnnotation.Annotated
-				&& symbol is INamedTypeSymbol namedType
-				&& namedType.IsValueType
-				&& namedType.IsGenericType
-				&& namedType.ConstructedFrom?.ToDisplayString() == "System.Nullable<T>"
-			)
+			    && symbol is INamedTypeSymbol { IsValueType: true, IsGenericType: true } namedType
+			    && namedType.ConstructedFrom.ToDisplayString() == "System.Nullable<T>")
+			{
 				return namedType.TypeArguments[0].TypeKind == TypeKind.Enum;
+			}
 
 			return false;
 		}