fix: hide the charge limit toggle on unsupported devices

cosmic-applet-battery/src/backend/mod.rs

@@ -214,24 +214,22 @@ pub enum PowerProfileUpdate {
 }
 
 // check if battery charging thresholds is set
-pub async fn get_charging_limit() -> bool {
+pub async fn get_charging_limit() -> anyhow::Result<bool> {
     if let Ok(conn) = Connection::system().await {
         if let Ok(backend) = get_power_backend(&conn, &BackendType::S76PowerDaemon).await {
             match backend {
                 Backend::S76PowerDaemon(proxy) => {
                     if let Ok((start, end)) = proxy.get_charge_thresholds().await {
-                        return start > 0 || end > 0;
+                        return Ok(start > 0 || end > 0);
                     }
                 }
                 Backend::PowerProfilesDaemon(_) => {
                     tracing::info!("Power Profiles Daemon is not supported.");
-
-                    return false;
                 }
             };
         }
     }
-    false
+    anyhow::bail!("Unsupported")
 }
 
 // set battery charging thresholds via s76 power_daemon