fix(imap): do not bubble up errors in IMAP candidate loop

Network errors such as timeouts should not break out of the loop
by bubbling up errors. There may be more candidates to try,
breaking out of the loop skips trying them.

src/imap.rs

@@ -395,18 +395,30 @@ impl Imap {
 
             match login_res {
                 Ok(mut session) => {
-                    let capabilities = determine_capabilities(&mut session).await?;
+                    let capabilities = match determine_capabilities(&mut session).await {
+                        Ok(capabilities) => capabilities,
+                        Err(err) => {
+                            warn!(context, "Failed to determine capabilities: {err:#}.");
+                            continue;
+                        }
+                    };
                     let resync_request_sender = self.resync_request_sender.clone();
 
                     let session = if capabilities.can_compress {
                         info!(context, "Enabling IMAP compression.");
-                        let compressed_session = session
+                        let compressed_session = match session
                             .compress(|s| {
                                 let session_stream: Box<dyn SessionStream> = Box::new(s);
                                 session_stream
                             })
                             .await
-                            .context("Failed to enable IMAP compression")?;
+                        {
+                            Ok(compressed_session) => compressed_session,
+                            Err(err) => {
+                                warn!(context, "Failed to enable IMAP compression: {err:#}.");
+                                continue;
+                            }
+                        };
                         Session::new(
                             compressed_session,
                             capabilities,