Fixed: NullRef in SchemaBuilder when sending payload without optional Provider.Settings fields

src/Lidarr.Http/ClientSchema/SchemaBuilder.cs

@@ -46,8 +46,11 @@ namespace Lidarr.Http.ClientSchema
             {
                 var field = fields.Find(f => f.Name == mapping.Field.Name);
 
+                if (field != null)
+                {
                     mapping.SetterFunc(target, field.Value);
                 }
+            }
 
             return target;
         }