js: Remove unused catch bindings

Optional catch bindings have been supported for quite a while now,
so we can treat unused error bindings in catch statements like any
other unused variable.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/3684>

js/ui/components/automountManager.js

@@ -54,7 +54,7 @@ class AutomountManager {
             const [inhibited] =
                 await this._session.IsInhibitedAsync(GNOME_SESSION_AUTOMOUNT_INHIBIT);
             this._inhibited = inhibited;
-        } catch (e) {}
+        } catch {}
     }
 
     _startupMountAll() {