Define specific error type for customer ID lookup failures in processUserLogin

[coderabbitai]

In the processUserLogin function, consider defining a custom error class, such as CustomerIDNotFoundError, to provide more context for error handling when the customer ID is not found for a given persona ID. This will enhance error handling upstream by providing more specific context.\n\nPR URL: https://github.com/rustymotors/server/pull/2037\nComment URL: #2037 (comment)