fix(cookie-banner): disconnect observer in load() error path

When fetchJSON failed, load() unconditionally overwrote this.observer
with a fresh MutationObserver, leaving any previous one observing the
DOM. Repeated load() calls that hit the catch branch leaked one
observer per call. Mirror the disconnect-first pattern already used in
activate().

Signed-off-by: Émile Ré <emile@probo.com>

packages/cookie-banner/src/client.ts

@@ -93,6 +93,9 @@ export class CookieBannerClient {
       config = await fetchJSON<BannerConfig>(configUrl);
     } catch {
       this.startDetector();
+      if (this.observer) {
+        this.observer.disconnect();
+      }
       this.observer = observeAndActivate({}, {});
       getConsent()._setReady({}, false);
       return;