fix: trace return null cause page crash (#15588)

web/app/(commonLayout)/app/(appDetailLayout)/[appId]/overview/tracing/panel.tsx

         ? LangfuseIcon
         : inUseTracingProvider === TracingProvider.opik
           ? OpikIcon
-          : null
+          : LangsmithIcon
 
   const [langSmithConfig, setLangSmithConfig] = useState<LangSmithConfig | null>(null)
   const [langFuseConfig, setLangFuseConfig] = useState<LangFuseConfig | null>(null)