Fix SDLNet Initialisation and error path (#3)

* Initialize RawSocketSerial::thread_active to false so that it doesn't try to cleanup uninitialized objects on error.

* Reorder main to avoid thread race conditions involving pin_map if listen_on_port fails

* Initialize SDL and SDLNet so that socket can be opened

src/MarlinSimulator/RawSocketSerial.h

@@ -37,6 +37,7 @@ class RawSocketSerial {
  }
  start_listen(ip);
  server_thread = std::thread(&RawSocketSerial::execute, this);
+ thread_active = true;
  }
 
  void stop() {
@@ -178,7 +179,7 @@ class RawSocketSerial {
  void write(const char* str) { while (*str) tx_buffer.write(*str++); }
  void write(const uint8_t* buffer, size_t size) { tx_buffer.write((uint8_t *)buffer, size); }
 
- bool thread_active = true;
+ bool thread_active = false;
  ServerInfo server{};
  uint8_t receive_buffer[ServerInfo::max_packet_size];
  uint8_t transmit_buffer[ServerInfo::max_packet_size];

src/MarlinSimulator/main.cpp

@@ -60,11 +60,16 @@ void simulation_main() {
 
 // Main code
 int main(int, char**) {
- Application app;
- std::thread simulation_loop(simulation_main);
+ SDL_Init(0);
+ SDLNet_Init();
 
+ // Listen before starting simulator loop to avoid
+ // thread synchronization issues if listen_on_port fails
  net_serial.listen_on_port(8099);
 
+ Application app;
+ std::thread simulation_loop(simulation_main);
+
  while (app.active) {
  app.update();
  app.render();
@@ -76,5 +81,8 @@ int main(int, char**) {
  simulation_loop.join();
  net_serial.stop();
 
+ SDLNet_Quit();
+ SDL_Quit();
+
  return 0;
 }