style: optimization code (#42679)

* style: optimization code

* style: use const replace themestyle init

components/empty/empty.tsx

@@ -6,14 +6,9 @@ const Empty: React.FC = () => {
   const [, token] = useToken();
 
   const bgColor = new TinyColor(token.colorBgBase);
-  let themeStyle: React.CSSProperties = {};
 
   // Dark Theme need more dark of this
-  if (bgColor.toHsl().l < 0.5) {
+  const themeStyle: React.CSSProperties = bgColor.toHsl().l < 0.5 ? { opacity: 0.65 } : {};
-    themeStyle = {
-      opacity: 0.65,
-    };
-  }
 
   return (
     <svg