pkgs/switch-report: fix vlan ordering

nix/pkgs/switch-report.nix

@@ -49,7 +49,19 @@ let
               map (net:
                 "${net} (`${toString config.site.net.${net}.vlan}`)"
               ) (builtins.sort (a: b:
-                config.site.net.${a}.vlan < config.site.net.${b}.vlan
+                let
+                  vlanA = config.site.net.${a}.vlan;
+                  vlanB = config.site.net.${b}.vlan;
+                in
+                  (
+                    if vlanA == null
+                    then 4096
+                    else vlanA
+                  ) < (
+                    if vlanB == null
+                    then 4096
+                    else vlanB
+                  )
               ) link.nets)
             )
           }|