Explicitly set the author ID to nil in the absence of a user ID + aut…

…hor.

WordPress/Classes/Models/Blog+Post.swift

@@ -55,9 +55,14 @@ extension Blog {
         post.postFormat = settings?.defaultPostFormat
         post.postType = Post.typeDefaultIdentifier
 
-        if let userID = userID, let author = getAuthorWith(id: userID) {
+        if let userID, let author = getAuthorWith(id: userID) {
             post.authorID = author.userID
             post.author = author.displayName
+        } else {
+            /// Explicitly set the author ID to nil, otherwise it will default
+            /// to the Core Data value of 0 which is a logic error.
+            post.authorID = nil
+            post.author = nil
         }
 
         try? context.obtainPermanentIDs(for: [post])
@@ -85,9 +90,14 @@ extension Blog {
         page.date_created_gmt = Date()
         page.remoteStatus = .sync
 
-        if let userID = userID, let author = getAuthorWith(id: userID) {
+        if let userID, let author = getAuthorWith(id: userID) {
             page.authorID = author.userID
             page.author = author.displayName
+        } else {
+            /// Explicitly set the author ID to nil, otherwise it will default
+            /// to the Core Data value of 0 which is a logic error.
+            page.authorID = nil
+            page.author = nil
         }
 
         try? context.obtainPermanentIDs(for: [page])