settings: Show notification when user/project settings fail to parse (#18122)

Closes #16876

We only ever showed parsing errors, but not if something failed to
deserialize.

Basically, if you had a stray `,` somewhere, we'd show a notification
for user errors, but only squiggly lines if you had a `[]` instead of a
`{}`.

The squiggly lines would only show up when there were schema errors.

In the case of `formatter` settings, for example, if someone put in a
`{}` instead of `[]`, we'd never show anything.

With this change we always show a notification if parsing user or
project settings fails.

(Right now, the error message might still be bad, but that's a separate
change)


Release Notes:

- Added a notification to warn users if their user settings or
project-local settings failed to deserialize.

Demo:


https://github.com/user-attachments/assets/e5c48165-f2f7-4b5c-9c6d-6ea74f678683

crates/zed/src/main.rs

@@ -34,7 +34,9 @@ use parking_lot::Mutex;
 use recent_projects::open_ssh_project;
 use release_channel::{AppCommitSha, AppVersion};
 use session::{AppSession, Session};
-use settings::{handle_settings_file_changes, watch_config_file, Settings, SettingsStore};
+use settings::{
+    handle_settings_file_changes, watch_config_file, InvalidSettingsError, Settings, SettingsStore,
+};
 use simplelog::ConfigBuilder;
 use smol::process::Command;
 use std::{
@@ -626,20 +628,28 @@ fn handle_settings_changed(error: Option<anyhow::Error>, cx: &mut AppContext) {
 
     for workspace in workspace::local_workspace_windows(cx) {
         workspace
-            .update(cx, |workspace, cx| match &error {
-                Some(error) => {
-                    workspace.show_notification(id.clone(), cx, |cx| {
-                        cx.new_view(|_| {
-                            MessageNotification::new(format!("Invalid settings file\n{error}"))
+            .update(cx, |workspace, cx| {
+                match error
+                    .as_ref()
+                    .and_then(|error| error.downcast_ref::<InvalidSettingsError>())
+                {
+                    Some(InvalidSettingsError::UserSettings { message }) => {
+                        workspace.show_notification(id.clone(), cx, |cx| {
+                            cx.new_view(|_| {
+                                MessageNotification::new(format!(
+                                    "Invalid user settings file\n{message}"
+                                ))
                                 .with_click_message("Open settings file")
                                 .on_click(|cx| {
                                     cx.dispatch_action(zed_actions::OpenSettings.boxed_clone());
                                     cx.emit(DismissEvent);
                                 })
-                        })
-                    });
+                            })
+                        });
+                    }
+                    None => workspace.dismiss_notification(&id, cx),
+                    _ => {}
                 }
-                None => workspace.dismiss_notification(&id, cx),
             })
             .log_err();
     }