fix(closing): window can be closing on event

src/background/background.js

@@ -266,6 +266,7 @@ app.on("ready", () => {
 					{
 						const id = arg[arg.length - 1].callback
 						arg[arg.length - 1] = (responce) => {
+							if(mainWindow)
 								mainWindow.webContents.send('callback', id, responce)
 						}
 					}