fix(webui): error on search confirm

webui/src/components/layout/Header.svelte

@@ -21,6 +21,8 @@
 
   async function onInput(event: CustomEvent<SelectorValue>) {
     const value = event.detail;
+    if (!value) return;
+
     switch (value.t) {
       case "Address":
         navigate(`/browse/${value.c}`);