fix: do not log error if watched folder is not configured

This may happen if Sent folder does not exist
but configuration option to watch it is enabled.

Author: link2xt

python/tests/test_1_online.py

@@ -381,7 +381,7 @@ def test_webxdc_download_on_demand(acfactory, data, lp):
     assert msgs_changed_event.data1 == msg2.chat.id
     assert msgs_changed_event.data2 == 0
 
-@pytest.mark.xfail(reason="Test server has no sentbox folder")
+
 def test_mvbox_sentbox_threads(acfactory, lp):
     lp.sec("ac1: start with mvbox thread")
     ac1 = acfactory.new_online_configuring_account(mvbox_move=True, sentbox_watch=True)

src/scheduler.rs

@@ -520,7 +520,10 @@ async fn fetch_idle(ctx: &Context, connection: &mut Imap, folder_meaning: Folder
     let (folder_config, watch_folder) = match convert_folder_meaning(ctx, folder_meaning).await {
         Ok(meaning) => meaning,
         Err(error) => {
-            error!(ctx, "Error converting IMAP Folder name: {:?}", error);
+            // Warning instead of error because the folder may not be configured.
+            // For example, this happens if the server does not have Sent folder
+            // but watching Sent folder is enabled.
+            warn!(ctx, "Error converting IMAP Folder name: {:?}", error);
             connection.connectivity.set_not_configured(ctx).await;
             connection
                 .fake_idle(ctx, None, FolderMeaning::Unknown)