fix: add missing optional chain on billingPlanDetails.name

Author: HarshMN2345

src/lib/layout/containerButton.svelte

@@ -13,7 +13,7 @@
         $organization?.billingPlanDetails?.group === BillingPlanGroup.Starter
             ? `Upgrade to add more ${title.toLocaleLowerCase()}`
             : `You've reached the ${title.toLocaleLowerCase()} limit for the ${
-                  $organization?.billingPlanDetails.name
+                  $organization?.billingPlanDetails?.name
               } plan`;
 
     export let disabled: boolean;