Lock mutex when accessing m_env in Server::~Server

src/server.cpp

@@ -1140,6 +1140,9 @@ Server::~Server()
 		}
 	}
 	
+	{
+		JMutexAutoLock envlock(m_env_mutex);
+
 		/*
 			Save players
 		*/
@@ -1151,6 +1154,7 @@ Server::~Server()
 		*/
 		dstream<<"Server: Saving environment metadata"<<std::endl;
 		m_env.saveMeta(m_mapsavedir);
+	}
 		
 	/*
 		Stop threads
@@ -1202,6 +1206,8 @@ void Server::stop()
 {
 	DSTACK(__FUNCTION_NAME);
 	
+	dout_server<<"Server: Stopping and waiting threads"<<std::endl;
+
 	// Stop threads (set run=false first so both start stopping)
 	m_thread.setRun(false);
 	m_emergethread.setRun(false);