fix: client crashes a program after destructor is called (#14)

Co-authored-by: kirkezz <iamkirkezz@gmail.com>

include/rconpp/client.h

@@ -16,6 +16,7 @@
 #include <vector>
 #include <iostream>
 #include <cstring>
+#include <atomic>
 #include <thread>
 #include <condition_variable>
 #include "utilities.h"
@@ -44,7 +45,7 @@ class RCONPP_EXPORT rcon_client {
 	std::thread queue_runner;
 
 public:
-	bool connected{false};
+	std::atomic<bool> connected{false};
 
 	std::function<void(const std::string_view& log)> on_log;
 

src/rconpp/client.cpp

@@ -241,10 +241,6 @@ void rconpp::rcon_client::start(bool return_after) {
 			}
 
 			for (const queued_request& request : requests_queued) {
-				// If we're closing the connection down, we need to back out.
-				if(!connected)
-					return;
-
 				// Send data to callback if it's been set.
 				if (request.callback)
 					request.callback(send_data_sync(request.data, request.id, request.type));
@@ -256,8 +252,6 @@ void rconpp::rcon_client::start(bool return_after) {
 		}
 	});
 
-	queue_runner.detach();
-
 	if(!return_after) {
 		block_calling_thread();
 	}