Properly close the renderqueue when shutting down

src/init.py

@@ -7,6 +7,8 @@ from collections import deque
 
 from PyQt6.QtCore import QObject, pyqtSignal
 from PyQt6.QtWidgets import QApplication
+
+from .render_queue import RenderQueue
 from .ui.main_window import MainWindow
 
 from src.api.api_server import start_server
@@ -45,7 +47,10 @@ def run() -> int:
     window: MainWindow = MainWindow()
     window.buffer_handler = buffer_handler
     window.show()
-    return sys.exit(app.exec())
+
+    return_code = app.exec()
+    RenderQueue.prepare_for_shutdown()
+    return sys.exit(return_code)
 
 
 class BufferingHandler(logging.Handler, QObject):