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

Author: sjasonsmith

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;
 }