Fix crash when using old tab to load item page

Oops, the new `canonicalAppearance` arguments couldn't handle being omitted rather than being null, due to a low-level SQL call site that cares about the difference.

This meant that loading an item page in an old tab, with an old copy of our JS, could cause a crash.

Now, the backend will be okay with queries from old pages, and respond the same as before!

This isn't a huge deal, because once everyone is on the new JS we won't send queries without this parameter anyway… but I like my optional arguments to actually BE optional, without surprises lurking >.>

src/server/loaders.js

@@ -1005,7 +1005,12 @@ const buildCanonicalPetStateForBodyLoader = (db, loaders) =>
               LIMIT 1`,
               nestTables: true,
             },
-            [bodyId, preferredColorId, fallbackColorId, gender === "fem"]
+            [
+              bodyId,
+              preferredColorId || "<ignore>",
+              fallbackColorId,
+              gender === "fem",
+            ]
           );
           const petState = normalizeRow(rows[0].pet_states);
           const petType = normalizeRow(rows[0].pet_types);