Fixed a few issues found during QA

Fixed an issue where you could be left on the settings screen after deleting/leaving a conversation
Fixed an issue where deleting the last contact/group/community from a device would result in linked devices not deleting the relevant conversation
Fixed an issue where leaving a group created a race condition where linked devices wouldn't remove the group

Session/Conversations/Settings/ThreadSettingsViewModel.swift

@@ -201,7 +201,12 @@ class ThreadSettingsViewModel: SessionTableViewModel<ThreadSettingsViewModel.Nav
                 .conversationSettingsQuery(threadId: threadId, userPublicKey: userPublicKey)
                 .fetchOne(db)
             
-            guard let threadViewModel: SessionThreadViewModel = maybeThreadViewModel else { return [] }
+            // If we don't get a `SessionThreadViewModel` then it means the thread was probably deleted
+            // so dismiss the screen
+            guard let threadViewModel: SessionThreadViewModel = maybeThreadViewModel else {
+                self?.dismissScreen(type: .popToRoot)
+                return []
+            }
             
             // Additional Queries
             let fallbackSound: Preferences.Sound = db[.defaultNotificationSound]

SessionMessagingKit/Sending & Receiving/Message Handling/MessageReceiver+ClosedGroups.swift

@@ -549,7 +549,7 @@ extension MessageReceiver {
                     try ClosedGroup.removeKeysAndUnsubscribe(
                         db,
                         threadId: threadId,
-                        removeGroupData: false,
+                        removeGroupData: (sender == userPublicKey),
                         calledFromConfigHandling: false
                     )
                 }

SessionMessagingKit/SessionUtil/Config Handling/SessionUtil+Contacts.swift

@@ -89,9 +89,6 @@ internal extension SessionUtil {
         let userPublicKey: String = getUserHexEncodedPublicKey(db)
         let targetContactData: ContactData = contactData.filter { $0.key != userPublicKey }
         
-        // If we only updated the current user contact then no need to continue
-        guard !targetContactData.isEmpty else { return }
-        
         // Since we don't sync 100% of the data stored against the contact and profile objects we
         // need to only update the data we do have to ensure we don't overwrite anything that doesn't
         // get synced

SessionMessagingKit/SessionUtil/Config Handling/SessionUtil+ConvoInfoVolatile.swift

@@ -85,9 +85,6 @@ internal extension SessionUtil {
             convo_info_volatile_iterator_advance(convoIterator)
         }
         convo_info_volatile_iterator_free(convoIterator) // Need to free the iterator
-
-        // If we don't have any conversations then no need to continue
-        guard !volatileThreadInfo.isEmpty else { return }
         
         // Get the local volatile thread info from all conversations
         let localVolatileThreadInfo: [String: VolatileThreadInfo] = VolatileThreadInfo.fetchAll(db)

SessionMessagingKit/SessionUtil/Config Handling/SessionUtil+UserGroups.swift

@@ -119,9 +119,6 @@ internal extension SessionUtil {
         }
         user_groups_iterator_free(groupsIterator) // Need to free the iterator
         
-        // If we don't have any conversations then no need to continue
-        guard !communities.isEmpty || !legacyGroups.isEmpty else { return }
-        
         // Extract all community/legacyGroup/group thread priorities
         let existingThreadInfo: [String: PriorityVisibilityInfo] = (try? SessionThread
             .select(.id, .variant, .pinnedPriority, .shouldBeVisible)

SessionMessagingKit/Shared Models/SessionThreadViewModel.swift

@@ -255,6 +255,8 @@ public struct SessionThreadViewModel: FetchableRecordWithRowId, Decodable, Equat
         let threadId: String = self.threadId
         let threadWasMarkedUnread: Bool? = self.threadWasMarkedUnread
         let markThreadAsReadIfNeeded: () -> () = {
+            // Only make this change if needed (want to avoid triggering a thread update
+            // if not needed)
             guard threadWasMarkedUnread == true else { return }
             
             Storage.shared.writeAsync { db in
@@ -289,16 +291,7 @@ public struct SessionThreadViewModel: FetchableRecordWithRowId, Decodable, Equat
                 let threadIsMessageRequest: Bool? = self.threadIsMessageRequest
                 
                 Storage.shared.writeAsync { db in
-                    // Only make this change if needed (want to avoid triggering a thread update
-                    // if not needed)
-                    if threadWasMarkedUnread == true {
-                        try SessionThread
-                            .filter(id: threadId)
-                            .updateAllAndConfig(
-                                db,
-                                SessionThread.Columns.markedAsUnread.set(to: false)
-                            )
-                    }
+                    markThreadAsReadIfNeeded()
                     
                     try Interaction.markAsRead(
                         db,