unique react key in playground editor buttons (#29836)

* unique React key in playground editor buttons

* second place

components/playground/CodeLanguagePicker.tsx

@@ -13,6 +13,7 @@ export const CodeLanguagePicker = () => {
       <SubNav.Links>
         {codeLanguages.map((language) => (
           <SubNav.Link
+            key={language.id}
             as={Link}
             href={`${routePath}?langId=${language.id}`}
             selected={language.id === currentLanguage.id}