Fix missing buttons on bottom bar when window is narrow (#3653)

* Delay offsetHeight query to account for reflow

* Handle invalid value if webview page was deleted

qt/aqt/toolbar.py

@@ -246,8 +246,18 @@ class BottomWebView(ToolbarWebView):
 
         self.hidden = False
         if self.mw.state == "review":
-            self.evalWithCallback(
+            # delay to account for reflow
-                "document.documentElement.offsetHeight", self.animate_height
+            def cb(height: int | None):
+                # "When QWebEnginePage is deleted, the callback is triggered with an invalid value"
+                if height is not None:
+                    self.animate_height(height)
+
+            self.mw.progress.single_shot(
+                50,
+                lambda: self.evalWithCallback(
+                    "document.documentElement.offsetHeight", cb
+                ),
+                False,
             )
         else:
             self.adjustHeightToFit()