[geary/mjog/draft-errors: 1/6] Geary.Imap.FolderSession: Fix null param critical with vala 0.50

[Michael Gratton <mjog src gnome org>]

commit 6530c66e28c930c51b5094a6040d690b3ae858e9
Author: Michael Gratton <mike vee net>
Date:   Sun Oct 25 12:55:28 2020 +1100

    Geary.Imap.FolderSession: Fix null param critical with vala 0.50
    
    Cancellable can be null, mark it as such - more fallout from
    GNOME/vala#299
    
    Fixes #1044

 src/engine/imap/api/imap-folder-session.vala | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/engine/imap/api/imap-folder-session.vala b/src/engine/imap/api/imap-folder-session.vala
index 8a2290cb8..3b777ee6a 100644
--- a/src/engine/imap/api/imap-folder-session.vala
+++ b/src/engine/imap/api/imap-folder-session.vala
@@ -85,8 +85,8 @@ private class Geary.Imap.FolderSession : Geary.Imap.SessionObject {
 
     public async FolderSession(ClientSession session,
                                Imap.Folder folder,
-                               Cancellable cancellable)
-        throws Error {
+                               GLib.Cancellable? cancellable)
+        throws GLib.Error {
         base(session);
         this.folder = folder;
         this.quirks = session.quirks;