Fix mem freeing in ComponentManager

cpp/arcticdb/processing/component_manager.cpp

@@ -20,7 +20,7 @@ std::vector<EntityId> ComponentManager::get_new_entity_ids(size_t count) {
 }
 
 void ComponentManager::decrement_entity_fetch_count(EntityId id) {
-    if (registry_.get<std::atomic<EntityFetchCount>>(id).fetch_sub(1) == 0) {
+    if (registry_.get<std::atomic<EntityFetchCount>>(id).fetch_sub(1) == 1) {
         // This entity will never be accessed again
         // Ideally would call registry_.destroy(id), or at least registry_.erase<std::shared_ptr<SegmentInMemory>>(id)
         // at this point. However, they are both slower than this, and would require taking a unique_lock on the