Use more conventional field order in Mutation

FacadeFuzz.cpp

@@ -164,20 +164,20 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
         case 0: {
           // Point write
           auto val = randomKey(arena);
-          mutations.push_back({keys[i].p, val.p, keys[i].len, val.len,
+          mutations.push_back({keys[i].p, keys[i].len, val.p, val.len,
                                weaselab::VersionedMap::Set});
           ++i;
         } break;
         case 1: {
           // Point clear
-          mutations.push_back({keys[i].p, nullptr, keys[i].len, 0,
+          mutations.push_back({keys[i].p, keys[i].len, nullptr, 0,
                                weaselab::VersionedMap::Clear});
           ++i;
         } break;
         case 2: {
           // Range clear
           if (i + 1 < int(keys.size())) {
-            mutations.push_back({keys[i].p, keys[i + 1].p, keys[i].len,
+            mutations.push_back({keys[i].p, keys[i].len, keys[i + 1].p,
                                  keys[i + 1].len,
                                  weaselab::VersionedMap::Clear});
             i += 2;