fix: TypeError for cds bind in MTX scenario (#482)

The `await cds.connect.to ('db')` is called here before `cds bind`
resolves the `credentials` property. In an MTX scenario this doesn't
matter though, as the credentials are fetched from Service Manager at
runtime. Subsequent subscriptions etc. also work fine with this patch.

hana/lib/HANAService.js

@@ -29,7 +29,7 @@ class HANAService extends SQLService {
 
   // REVISIT: Add multi tenant factory when clarified
   get factory() {
-    const driver = drivers[this.options.driver || this.options.credentials.driver]?.driver || drivers.default.driver
+    const driver = drivers[this.options.driver || this.options.credentials?.driver]?.driver || drivers.default.driver
     const isMultitenant = 'multiTenant' in this.options ? this.options.multiTenant : cds.env.requires.multitenancy
     const service = this
     return {