[geary/mjog/misc-criticals: 5/9] Geary.ImapEngine.AccountSynchronizer: Avoid a critical in the destructor

[Michael Gratton <mjog src gnome org>]

commit be0ce29a1b47a1abc777ded93545ab2dd9b8ca0c
Author: Michael Gratton <mike vee net>
Date:   Fri Jun 26 17:17:58 2020 +1000

    Geary.ImapEngine.AccountSynchronizer: Avoid a critical in the destructor
    
    Use a weak ref in the dtor when disconnecting from the folders signals
    to avoid reffing the folder, which may be destroyed already when the
    object is destroyed.

 src/engine/imap-engine/imap-engine-account-synchronizer.vala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/engine/imap-engine/imap-engine-account-synchronizer.vala 
b/src/engine/imap-engine/imap-engine-account-synchronizer.vala
index 1880b1504..21ea1c745 100644
--- a/src/engine/imap-engine/imap-engine-account-synchronizer.vala
+++ b/src/engine/imap-engine/imap-engine-account-synchronizer.vala
@@ -121,7 +121,7 @@ private class Geary.ImapEngine.RefreshFolderSync : FolderOperation {
     }
 
     ~RefreshFolderSync() {
-        Geary.Folder? folder = this.folder;
+        weak Geary.Folder? folder = this.folder;
         if (folder != null) {
             this.folder.closed.disconnect(on_folder_close);
         }