Product sync fails with SB-AT-SYNC-000014 when preferred distributor is unmapped

Where: Autotask product catalog sync (product → Synchronize to PSA). Reproduced on ISO Groep (shop.isogroep.nl) for DELL-WD25TB5 / Ingram Micro. Error SB-AT-SYNC-000014 points at Settings → Distributors → Mapping, a tab that is hidden unless the procurement feature flag, ConnectWise, or VanRoey BC is on.

What is happening: Since the last release, physical-product push to Autotask fails the entire catalog sync when the preferred distributor is not mapped to an Autotask Vendor company.

What should happen: Product catalog sync succeeds. Missing distributor→Vendor mapping skips Autotask ProductVendors (pre-TN-9256 behaviour). Autotask PO create still requires the mapping and can still throw SB-AT-SYNC-000014 — those tenants have the Mapping tab.

Who is affected: Autotask tenants without procurement / ConnectWise / VanRoey BC who sync products that have a preferred distributor. High urgency: catalog sync is broken in production; the error names a page that does not exist in their UI.

Root cause: TN-9256 (6e8c0ded65, now on release) extracted ProductVendors upsert into AutotaskProductVendorService and stopped silently skipping an unmapped preferred distributor on product sync. That was meant to populate PO Primary Vendor. PO create already upserts ProductVendors itself. Failing catalog sync for tenants who cannot open Mapping is a release regression.

Fix: On product catalog sync, restore skip when the distributor has no Autotask Vendor link. Keep the classified throw on the PO-create path (requireMappedAutotaskVendor).

Related: TN-9256