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/status/network.js

@@ -2126,7 +2126,7 @@ class Indicator extends SystemIndicator {
                 const state = await this._client.check_connectivity_async(null);
                 if (state >= NM.ConnectivityState.FULL)
                     this._portalHandler.removeConnection(path);
-            } catch (e) { }
+            } catch {}
         });
 
         this._client.connectObject(