[Projection tooling] Investigate demangler errors for async functions

[jkurdek]

The following errors occur when running demangler on purchase(options:) and products(for:)

Error while processing node 'purchase ($s8StoreKit7ProductV8purchase9confirmIn7optionsAC14PurchaseResultOSo8NSWindowC_ShyAC0H6OptionVGtYaKF)': Expected an index payload, but this has a None payload
Error while processing node 'products ($s8StoreKit7ProductV8products3forSayACGx_tYaKSlRzSS7ElementRtzlFZ)': Expected an index payload, but this has a None payload