fix: add better error handling for uninitialized billing plugin

- Fix TypeError when accessing providerConfig on undefined billing plugin
- Add proper type safety: useBillingPlugin now returns BillingPlugin | undefined
- Add clear error message when plugin hasn't been initialized
- Update README quickstart with concise provider response examples

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

README.md

@@ -100,18 +100,21 @@ export default buildConfig({
 const payment = await payload.create({
   collection: 'payments',
   data: {
-    provider: 'stripe',
+    provider: 'stripe',  // or 'mollie' or 'test'
     amount: 5000,        // $50.00 in cents
     currency: 'USD',
     description: 'Product purchase',
     status: 'pending',
   }
 })
-
-// Payment is automatically initialized with Stripe
-console.log(payment.providerId)  // Stripe PaymentIntent ID
 ```
 
+**What you get back:**
+
+- **Stripe**: `providerId` = PaymentIntent ID, `providerData.raw.client_secret` for Stripe.js
+- **Mollie**: `providerId` = Transaction ID, `providerData.raw._links.checkout.href` for redirect URL
+- **Test**: `providerId` = Test payment ID, `providerData.raw.paymentUrl` for interactive test UI
+
 ## Payment Providers
 
 ### Stripe

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@xtr-dev/payload-billing",
-  "version": "0.1.14",
+  "version": "0.1.15",
   "description": "PayloadCMS plugin for billing and payment provider integrations with tracking and local testing",
   "license": "MIT",
   "type": "module",

src/collections/hooks.ts

@@ -4,6 +4,13 @@ import { useBillingPlugin } from '../plugin/index'
 
 export const initProviderPayment = async (payload: Payload, payment: Partial<Payment>): Promise<Partial<Payment>> => {
   const billing = useBillingPlugin(payload)
+
+  if (!billing) {
+    throw new Error(
+      'Billing plugin not initialized. Make sure the billingPlugin is properly configured in your Payload config and that Payload has finished initializing.'
+    )
+  }
+
   if (!payment.provider || !billing.providerConfig[payment.provider]) {
     throw new Error(`Provider ${payment.provider} not found.`)
   }

src/plugin/index.ts

@@ -13,7 +13,7 @@ type BillingPlugin = {
   }
 }
 
-export const useBillingPlugin = (payload: Payload) => singleton.get(payload) as BillingPlugin
+export const useBillingPlugin = (payload: Payload) => singleton.get(payload) as BillingPlugin | undefined
 
 export const billingPlugin = (pluginConfig: BillingPluginConfig = {}) => (config: Config): Config => {
   if (pluginConfig.disabled) {