A few minor refactorings for IMAP ! usage

Author: jstedfast

MailKit/Net/Imap/ImapFolder.cs

@@ -318,10 +318,12 @@ static string SelectOrExamine (FolderAccess access)
 
 		static Task UntaggedQResyncFetchHandler (ImapEngine engine, ImapCommand ic, int index, bool doAsync)
 		{
+			var folder = ic.Folder!;
+
 			if (doAsync)
-				return ic.Folder!.OnUntaggedFetchResponseAsync (engine, index, ic.CancellationToken);
+				return folder.OnUntaggedFetchResponseAsync (engine, index, ic.CancellationToken);
 
-			ic.Folder!.OnUntaggedFetchResponse (engine, index, ic.CancellationToken);
+			folder.OnUntaggedFetchResponse (engine, index, ic.CancellationToken);
 
 			return Task.CompletedTask;
 		}

MailKit/Net/Imap/ImapUtils.cs

@@ -2974,13 +2974,14 @@ public static async Task ParseThreadsAsync (ImapEngine engine, uint uidValidity,
 		public static Task UntaggedThreadHandler (ImapEngine engine, ImapCommand ic, int index, bool doAsync)
 		{
 			var threads = new List<MessageThread> ();
+			var folder = ic.Folder!;
 
 			ic.UserData = threads;
 
 			if (doAsync)
-				return ParseThreadsAsync (engine, ic.Folder!.UidValidity, threads, ic.CancellationToken);
+				return ParseThreadsAsync (engine, folder.UidValidity, threads, ic.CancellationToken);
 
-			ParseThreads (engine, ic.Folder!.UidValidity, threads, ic.CancellationToken);
+			ParseThreads (engine, folder.UidValidity, threads, ic.CancellationToken);
 
 			return Task.CompletedTask;
 		}