You're welcome, LiviaCH. 😊 I am having developer software installed. In Xcode I can look into the source code for the frameworks used by the system applications. And occasionally we can see explanations for the error codes in the comments, pure luck.
Other errors you may be seeing in Photos:
Permission errors:
PHPhotosErrorAccessRestricted API_AVAILABLE = 3310 // Access restricted by system configuration
PHPhotosErrorAccessUserDenied API_AVAILABLE= 3311, // The user has denied access
Errors with older, incompatible software installed:
PHPhotosErrorInvalid API_DEPRECATED_WITH_REPLACEMENT = -1, // DEPRECATED An unknown error occured