Resolve #936 (#941)

* Resolve #936

* Remember to not search *only* typereaders for primitives 😒

src/Discord.Net.Commands/Builders/ModuleClassBuilder.cs

@@ -274,15 +274,8 @@ namespace Discord.Commands
 
             if (builder.TypeReader == null)
             {
-                var readers = service.GetTypeReaders(paramType);
-                TypeReader reader = null;
-
-                if (readers != null)
-                    reader = readers.FirstOrDefault().Value;
-                else
-                    reader = service.GetDefaultTypeReader(paramType);
-
-                builder.TypeReader = reader;
+                builder.TypeReader = service.GetDefaultTypeReader(paramType)
+                    ?? service.GetTypeReaders(paramType)?.FirstOrDefault().Value;
             }
         }