fix(UI): hang by unexpected nullptr in StandardLayout calculation

Author: fxliang

WeaselUI/StandardLayout.cpp

@@ -139,6 +139,8 @@ bool weasel::StandardLayout::_IsHighlightOverCandidateWindow(CRect& rc,
   Gdiplus::Region hlRegion(&hlPath);
   Gdiplus::Region* tmpRegion = hlRegion.Clone();
 
+  if (!tmpRegion)
+    return false;
   tmpRegion->Xor(&bgRegion);
   tmpRegion->Exclude(&bgRegion);