fix(core): improve error handling in tree parser

When tree parsing fails in Engine::insert, properly cleanup by removing
the path from tree map. This prevents invalid states from lingering.

Author: yingmanwumen

crates/echolysis-core/src/engine/insert.rs

@@ -16,7 +16,13 @@ impl Engine {
     pub fn insert(&self, path: Arc<PathBuf>, source: Arc<String>) -> Option<()> {
         let mut parser = self.language.parser();
         let query = self.language.query();
-        let tree = parser.parse(source.as_str(), None)?;
+        let tree = match parser.parse(source.as_str(), None) {
+            Some(tree) => tree,
+            None => {
+                self.remove(path);
+                return None;
+            }
+        };
         let indexed_tree = IndexedTree::new(path.clone(), source, tree, query);
 
         match self.tree_map.entry(path) {

crates/echolysis-lsp/src/server/fs_watcher.rs

@@ -135,6 +135,8 @@ impl Server {
     }
 
     // Handle filesystem events for code duplication analysis
+    // FIXME: There are bugs when dealing with directories. Fix it so that we can handle directory
+    // changes correctly
     async fn do_handle_fs_event(&self, event: notify::Event) {
         use notify::{event::*, EventKind};