chore: Fix several style lints (#17488)

It's not comprehensive enough to start linting on `style` group, but
hey, it's a start.

Release Notes:

- N/A

crates/diagnostics/src/toolbar_controls.rs

@@ -18,7 +18,7 @@ impl Render for ToolbarControls {
             let editor = editor.read(cx);
             include_warnings = editor.include_warnings;
             has_stale_excerpts = !editor.paths_to_update.is_empty();
-            is_updating = editor.update_paths_tx.len() > 0
+            is_updating = !editor.update_paths_tx.is_empty()
                 || editor
                     .project
                     .read(cx)
@@ -84,6 +84,12 @@ impl ToolbarItemView for ToolbarControls {
     }
 }
 
+impl Default for ToolbarControls {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl ToolbarControls {
     pub fn new() -> Self {
         ToolbarControls { editor: None }