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/dbusServices/screencast/screencastService.js

@@ -313,7 +313,7 @@ class Recorder extends Signals.EventEmitter {
             // non-pipeline-related failures.
             this._updateServiceCrashBlocklist(
                 [...this._blocklistFromPreviousCrashes, pipelineConfig.id]);
-        } catch (error) {
+        } catch {
             this._tryNextPipeline();
             return;
         }