Fix a use of an invalid iterator

VersionedMap.cpp

@@ -955,7 +955,10 @@ struct __attribute__((__visibility__("hidden"))) VersionedMap::Impl {
           if (engulfLeft && engulfRight) {
             insert({next->getKey(), next->keyLen}, {}, /*endRange*/ true, copy);
             if (found) {
-              remove(iter);
+              move<std::memory_order_relaxed, false>(copy, latestVersion);
+              // Point to the same entry as iter pointed to, but it's not
+              // invalidated
+              remove(copy);
             }
           } else if (engulfLeft) {
             assert(found);