Return placeholder instead of null

- Placeholder value when no windows active
- Empty string window name and class
- Avoid `null` for easier parsing

src/main.rs

@@ -14,7 +14,7 @@ struct Args {
 
 #[derive(Debug, Clone, Serialize, PartialEq, Eq)]
 struct State {
-    active_window: Option<WindowInfo>,
+    active_window: WindowInfo,
     workspaces: Vec<Workspace>,
 }
 
@@ -28,8 +28,18 @@ struct Workspace {
 #[derive(Debug, Clone, Serialize, PartialEq, Eq)]
 struct WindowInfo {
     id: u32,
-    name: Option<String>,
+    name: String,
-    class: Option<String>,
+    class: String,
+}
+
+impl WindowInfo {
+    fn placeholder() -> Self {
+        Self {
+            id: 0,
+            name: String::new(),
+            class: String::new(),
+        }
+    }
 }
 
 xcb::atoms_struct! {
@@ -119,7 +129,7 @@ impl X11 {
             })
             .collect();
 
-        let mut active_window = None;
+        let mut active_window = WindowInfo::placeholder();
 
         for id in client_ids {
             // Skip dock/panel windows
@@ -153,16 +163,18 @@ impl X11 {
 
             // Check if this is the active window
             if effective_active_id == Some(id) {
-                active_window = Some(window.clone());
+                active_window = window.clone();
             }
 
             workspace.windows.push(window);
         }
 
         // If we still don't have an active window, try to find the focused window
-        if active_window.is_none() {
+        if active_window.id == 0 {
             if let Some(id) = effective_active_id {
-                active_window = self.window_info(id).ok();
+                if let Ok(window) = self.window_info(id) {
+                    active_window = window;
+                }
             }
         }
 
@@ -242,11 +254,13 @@ impl X11 {
 
         let name = self
             .property_bytes_opt(window, self.atoms.net_wm_name, self.atoms.utf8_string)?
-            .and_then(|bytes| String::from_utf8(bytes).ok());
+            .and_then(|bytes| String::from_utf8(bytes).ok())
+            .unwrap_or_default();
 
         let class = self
             .property_bytes_opt(window, self.atoms.wm_class, x::ATOM_STRING)?
-            .map(|bytes| parse_wm_class(&bytes));
+            .map(|bytes| parse_wm_class(&bytes))
+            .unwrap_or_default();
 
         Ok(WindowInfo { id, name, class })
     }