fix: crash on fetchResultsController perform - WPB-22117 (#4003)

Author: netbe

WireDomain/Sources/WireDomain/Synchronization/ConversationUpdatesGenerator.swift

@@ -49,16 +49,16 @@ public final class ConversationUpdatesGenerator: NSObject, ConversationUpdatesGe
             fetchedResultsController = createFetchRequestController()
             fetchedResultsController?.delegate = self
         }
+        await context.perform {
+            do {
+                try self.fetchedResultsController?.performFetch()
+            } catch {
+                WireLogger.conversation.error("error fetching conversations: \(String(describing: error))")
+            }
 
-        do {
-            try fetchedResultsController?.performFetch()
-        } catch {
-            WireLogger.conversation.error("error fetching conversations: \(String(describing: error))")
-        }
+            let conversations = self.fetchedResultsController?.fetchedObjects ?? []
+            for conversation in conversations {
 
-        let conversations = fetchedResultsController?.fetchedObjects ?? []
-        for conversation in conversations {
-            await context.perform {
                 if let id = conversation.qualifiedID {
                     self.onConversationUpdated(UpdateConversationItem(
                         repository: self.repository,