Explicitly check for existence of links before formatting

Author: Matthias Gessinger

src/Client/src/Asp.Versioning.Http.Client/net#.0/ILoggerExtensions.cs

@@ -19,7 +19,7 @@ internal static void ApiVersionDeprecated(
         SunsetPolicy sunsetPolicy )
     {
         var sunsetDate = FormatDate( sunsetPolicy.Date );
-        var additionalInfo = FormatLinks( sunsetPolicy.Links );
+        var additionalInfo = FormatLinks( sunsetPolicy );
 
         ApiVersionDeprecated(
             logger,
@@ -46,7 +46,7 @@ internal static void NewApiVersionAvailable(
         SunsetPolicy sunsetPolicy )
     {
         var sunsetDate = FormatDate( sunsetPolicy.Date );
-        var additionalInfo = FormatLinks( sunsetPolicy.Links );
+        var additionalInfo = FormatLinks( sunsetPolicy );
 
         NewApiVersionAvailable(
             logger,
@@ -70,6 +70,16 @@ static partial void NewApiVersionAvailable(
     private static string FormatDate( DateTimeOffset? date ) =>
         date.HasValue ? date.Value.ToString( CultureInfo.CurrentCulture ) : "<unspecified>";
 
+    private static string[] FormatLinks( SunsetPolicy sunsetPolicy )
+    {
+        if ( !sunsetPolicy.HasLinks )
+        {
+            return [];
+        }
+
+        return FormatLinks( sunsetPolicy.Links );
+    }
+
     private static string[] FormatLinks( IList<LinkHeaderValue> links )
     {
         // <Title> (<Language>[,<Language>]): <Url>