Fix more race conditions if you exit during game bootup

Core/System.cpp

@@ -636,6 +636,9 @@ bool PSP_InitStart(const CoreParameter &coreParam) {
 			}
 		}
 
+		// Use this to test exit-during-boot and other exceptional cases.
+		// sleep_ms(6000, "test");
+
 		g_CoreParameter.fileType = fileType;
 
 		// TODO: The reason we pass in g_CoreParameter.errorString here is that it's persistent -

GPU/Common/FramebufferManagerCommon.cpp

@@ -2874,7 +2874,7 @@ void FramebufferManagerCommon::NotifyRenderResized(const DisplayLayoutConfig &co
 	PSP_CoreParameter().renderHeight = h;
 	PSP_CoreParameter().renderScaleFactor = scaleFactor;
 
-	if (UpdateRenderSize(msaaLevel)) {
+	if (draw_ && UpdateRenderSize(msaaLevel)) {
 		draw_->StopThreads();
 		DestroyAllFBOs();
 		draw_->StartThreads();

UI/EmuScreen.cpp

@@ -460,13 +460,20 @@ EmuScreen::~EmuScreen() {
 	std::string gameID = g_paramSFO.GetValueString("DISC_ID");
 	g_Config.TimeTracker().Stop(gameID);
 
-	// Should not be able to quit during boot, as boot can't be cancelled.
-	_dbg_assert_(!bootPending_);
-	if (!bootPending_) {
-		Achievements::UnloadGame();
-		PSP_Shutdown(true);
+	if (bootPending_) {
+		// We probably quit during boot, got blocked in lostdevice, and then didn't end up in update again to call PSP_InitUpdate.
+		// So we need to finish and join the boot thread before we can exit.
+		_dbg_assert_(PollBootState() != BootState::Booting);
+		// Make sure we join the boot thread, by calling PSP_InitUpdate.
+		std::string error_string = "(unknown error)";
+		PSP_InitUpdate(&error_string);
+		ERROR_LOG(Log::G3D, "Quit during boot, not good. %s", error_string.c_str());
+		bootPending_ = false;
 	}
 
+	Achievements::UnloadGame();
+	PSP_Shutdown(true);
+
 	// If achievements are disabled in the global config, let's shut it down here.
 	if (!g_Config.bAchievementsEnable) {
 		Achievements::Shutdown();