Don't kill the WebView on aboutToQuit (#4174)

Webview: Destroy on app.lastWindowClosed

- Don't kill the WebView on aboutToQuit
  Turns out, PyQt5's implementation of QApplication emits that signal
  every time the user types anything on the input line, when running
  Python interactively.

Author: ferdnyc

src/classes/app.py

@@ -309,7 +309,7 @@ def get_settings(self):
     def show_errors(self):
         count = len(self.errors)
         if count > 0:
-            self.log.warning("Displaying {} startup messages".format(count))
+            self.log.warning("Displaying %d startup messages", count)
         while self.errors:
             error = self.errors.pop(0)
             error.show()
@@ -320,6 +320,7 @@ def _tr(self, message):
     @pyqtSlot()
     def cleanup(self):
         """aboutToQuit signal handler for application exit"""
+        self.log.debug("Saving settings in app.cleanup")
         try:
             self.settings.save()
         except Exception:

src/windows/views/webview.py

@@ -3209,7 +3209,8 @@ def __init__(self, window):
         # Connect shutdown signals
         app.aboutToQuit.connect(self.redraw_audio_timer.stop)
         app.aboutToQuit.connect(self.cache_renderer.stop)
-        app.aboutToQuit.connect(self.deleteLater)
+        app.lastWindowClosed.connect(self.deleteLater)
 
         # Delay the start of cache rendering
         QTimer.singleShot(1500, self.cache_renderer.start)
+