SKALE-4939 fix crash on invalid zmq message

zmq_src/ZMQServer.cpp

@@ -219,7 +219,7 @@ pair <string, shared_ptr<zmq::message_t>> ZMQServer::receiveMessage() {
     if (!identity->more()) {
         checkForExit();
         // something terrible happened
-        spdlog::error("Fatal error: zmq_msg_more(identity) returned false. Existing.");
+        spdlog::error("Fatal error: zmq_msg_more(identity) returned false. Exiting.");
         exit(-12);
     }
 
@@ -276,7 +276,7 @@ void ZMQServer::doOneServerLoop() {
     Json::Value result;
     result["status"] = ZMQ_SERVER_ERROR;
 
-    shared_ptr <zmq::message_t> identity = nullptr;
+    shared_ptr <zmq::message_t> identity = make_shared<zmq::message_t>();
     string msgStr;
 
     try {
@@ -313,7 +313,7 @@ void ZMQServer::doOneServerLoop() {
             incomingQueue.at(index).enqueue(element);
         }
 
-    } catch (ExitRequestedException) {
+    } catch (ExitRequestedException&) {
         throw;
     } catch (exception &e) {
         checkForExit();