Handle formatter errors, and save anyway (#3684)

If formatting fails, report error to log and save without formatting.

helix-view/src/document.rs

@@ -543,7 +543,8 @@ impl Document {
             }
 
             if let Some(fmt) = formatting {
-                let transaction = fmt.await?;
+                match fmt.await {
+                    Ok(transaction) => {
                         let success = transaction.changes().apply(&mut text);
                         if !success {
                             // This shouldn't happen, because the transaction changes were generated
@@ -551,6 +552,12 @@ impl Document {
                             log::error!("failed to apply format changes before saving");
                         }
                     }
+                    Err(err) => {
+                        // formatting failed: report error, and save file without modifications
+                        log::error!("{}", err);
+                    }
+                }
+            }
 
             let mut file = File::create(path).await?;
             to_writer(&mut file, encoding, &text).await?;