To One relationship with mapped relationship name results in crash while trying to sync

[GabrielHauber]

Steps to reproduce:

1. Define a content model SomeModel in Contentful with a to-one relationship to another model SomeOtherModel. Let's call this relationship in Contentful toOneRelationship
2. Define the core data model with the to-one relationship, but in the core data model, call the relationship justOne
3. Define the core data NSManagedObject class as EntryPersistable, with the following field mapping:

class SomeOtherModel: NSManagedObject, EntryPersistable {}
class SomeModel: NSManagedObject, EntryPersistable {
    // this is called "toOneRelationship" in the Contentful model
    @NSManaged var justOne: SomeOtherModel?

    static func fieldMapping() -> [FieldName: String] {
        [
            "toOneRelationship": "justOne"
        ]
    }
}

During the sync operation, ContentfulPersistence will attempt to set the relationship on this managed object using the toOneRelationship name, rather than the justOne field name, resulting in a crash.

Only workaround seems to be to rename the relationship in the Contentful model definition.

[GabrielHauber]

… and I found that it actually works.
The problem was a stale cache - I had been using the old property name in the managed object model, decided there was a better name, renamed it in Core Data, updated the mapping, etc. Also had deleted the persistent store and created from scratch. However, ContentfulPersistence had a cache on disk containing the old mapping. After I removed the app and reinstalled (which obviously removed the cache) then it started working.