 - The form submission event.
         */
        function handleFormSubmit(event) {
          event.preventDefault();
          const url = endpointUrlInput.value.trim();

          // Update URL query parameter, catching potential security errors in sandboxed environments
          try {
            const currentUrl = new URL(window.location);
            currentUrl.searchParams.set("endpoint", url);
            window.history.pushState({}, "", currentUrl);
          } catch (e) {
            console.warn