Rework extension-related errors (#34620)

Before:
<img width="1728" height="1079" alt="before"
src="https://github.com/user-attachments/assets/4ab19211-8de4-458d-a835-52de859b7b20"
/>

After:
<img width="1728" height="1079" alt="after"
src="https://github.com/user-attachments/assets/231c9362-a0b0-47ae-b92e-de6742781d36"
/>

Makes clear which path is causing the FS error and removes backtraces
from logging.

Release Notes:

- N/A

crates/extension_host/src/extension_host.rs

@@ -1313,11 +1313,18 @@ impl ExtensionStore {
                     }
 
                     for snippets_path in &snippets_to_add {
-                        if let Some(snippets_contents) = fs.load(snippets_path).await.log_err() {
+                        match fs
+                            .load(snippets_path)
+                            .await
+                            .with_context(|| format!("Loading snippets from {snippets_path:?}"))
+                        {
+                            Ok(snippets_contents) => {
                                 proxy
                                     .register_snippet(snippets_path, &snippets_contents)
                                     .log_err();
                             }
+                            Err(e) => log::error!("Cannot load snippets: {e:#}"),
+                        }
                     }
                 }
             })
@@ -1331,22 +1338,27 @@ impl ExtensionStore {
 
                 let extension_path = root_dir.join(extension.manifest.id.as_ref());
                 let wasm_extension = WasmExtension::load(
-                    extension_path,
+                    &extension_path,
                     &extension.manifest,
                     wasm_host.clone(),
                     &cx,
                 )
-                .await;
+                .await
+                .with_context(|| format!("Loading extension from {extension_path:?}"));
 
-                if let Some(wasm_extension) = wasm_extension.log_err() {
-                    wasm_extensions.push((extension.manifest.clone(), wasm_extension));
-                } else {
+                match wasm_extension {
+                    Ok(wasm_extension) => {
+                        wasm_extensions.push((extension.manifest.clone(), wasm_extension))
+                    }
+                    Err(e) => {
+                        log::error!("Failed to load extension: {e:#}");
                         this.update(cx, |_, cx| {
                             cx.emit(Event::ExtensionFailedToLoad(extension.manifest.id.clone()))
                         })
                         .ok();
                     }
                 }
+            }
 
             this.update(cx, |this, cx| {
                 this.reload_complete_senders.clear();

crates/extension_host/src/headless_host.rs

@@ -173,9 +173,8 @@ impl HeadlessExtensionStore {
             return Ok(());
         }
 
-        let wasm_extension: Arc<dyn Extension> = Arc::new(
-            WasmExtension::load(extension_dir.clone(), &manifest, wasm_host.clone(), &cx).await?,
-        );
+        let wasm_extension: Arc<dyn Extension> =
+            Arc::new(WasmExtension::load(&extension_dir, &manifest, wasm_host.clone(), &cx).await?);
 
         for (language_server_id, language_server_config) in &manifest.language_servers {
             for language in language_server_config.languages() {

crates/extension_host/src/wasm_host.rs

@@ -715,7 +715,7 @@ fn parse_wasm_extension_version_custom_section(data: &[u8]) -> Option<SemanticVe
 
 impl WasmExtension {
     pub async fn load(
-        extension_dir: PathBuf,
+        extension_dir: &Path,
         manifest: &Arc<ExtensionManifest>,
         wasm_host: Arc<WasmHost>,
         cx: &AsyncApp,