do not save window state when window is minimized

this happens when the window is minimized on Windows. Restoring the
window size causes the application not available since the window size
is zero.

v2/src/shiba.rs

@@ -519,8 +519,10 @@ where
         let data_dir = self.config.data_dir();
         if self.config.window().restore {
             if let Some(state) = self.renderer.window_state() {
-                log::debug!("Saving window state as persistent data: {:?}", state);
-                data_dir.save(&state)?;
+                if state.height > 0 && state.width > 0 {
+                    log::debug!("Saving window state as persistent data: {:?}", state);
+                    data_dir.save(&state)?;
+                }
             }
         }
         data_dir.save_recent_files(self.history.iter(), self.config.max_recent_files())?;