fix: undefined (reading 'billingNextInvoiceDate')

When moving to a page without $organization, org is undefined and results in this "undefined (reading 'billingNextInvoiceDate')" error.

Author: stnguyen90

src/lib/stores/billing.ts

@@ -287,6 +287,7 @@ export function checkForEnterpriseTrial(org: Organization) {
 }
 
 export function calculateEnterpriseTrial(org: Organization) {
+    if (!org || !org.billingNextInvoiceDate) return 0;
     const endDate = new Date(org.billingNextInvoiceDate);
     const startDate = new Date(org.billingCurrentInvoiceDate);
     const today = new Date();