update failover error

Author: linglingye001

src/AzureAppConfigurationImpl.ts

@@ -698,6 +698,6 @@ function getValidFeatureFlagSelectors(selectors?: SettingSelector[]): SettingSel
 }
 
 function isFailoverableError(error: any): boolean {
-    return isRestError(error) && (error.statusCode === 401 || error.statusCode === 403 || error.statusCode === 408 || error.statusCode === 429 ||
-        (error.statusCode !== undefined && error.statusCode >= 500));
+    return isRestError(error) && error.statusCode !== undefined &&
+        (error.statusCode === 401 || error.statusCode === 403 || error.statusCode === 408 || error.statusCode === 429 || error.statusCode >= 500);
 }