IcingaDB: Don't sync partially initialised objects

lib/icingadb/icingadb-objects.cpp

@@ -559,14 +559,27 @@ std::vector<std::vector<intrusive_ptr<ConfigObject>>> IcingaDB::ChunkObjects(std
 
 	chunks.reserve((std::distance(offset, end) + chunkSize - 1) / chunkSize);
 
+	auto emplaceChunk ([&chunks](decltype(objects)::const_iterator from, decltype(objects)::const_iterator to) {
+		chunks.emplace_back(std::vector<ConfigObject::Ptr>());
+
+		// If we encounter not yet activated objects, i.e. they are currently being loaded and are about to
+		// be activated, but are still partially initialised, we want to exclude them from the config dump
+		// before we end up in a nullptr deference and crash the Icinga 2 process. Should these excluded objects
+		// later reach the activation process, they will be captured via the `OnActiveChanged` event and processed
+		// in IcingaDB::VersionChangedHandler() as runtime updates.
+		std::copy_if(from, to, std::back_inserter(chunks.back()), [](const ConfigObject::Ptr& obj) {
+			return obj->IsActive();
+		});
+	});
+
 	while (std::distance(offset, end) >= chunkSize) {
 		auto until (offset + chunkSize);
-		chunks.emplace_back(offset, until);
+		emplaceChunk(offset, until);
 		offset = until;
 	}
 
 	if (offset != end) {
-		chunks.emplace_back(offset, end);
+		emplaceChunk(offset, end);
 	}
 
 	return chunks;