fix(tui): prevent crash when theme search returns no results (#10565)

packages/opencode/src/cli/cmd/tui/ui/dialog-select.tsx

@@ -149,7 +149,8 @@ export function DialogSelect<T>(props: DialogSelectProps<T>) {
 
   function moveTo(next: number, center = false) {
     setStore("selected", next)
-    props.onMove?.(selected()!)
+    const option = selected()
+    if (option) props.onMove?.(option)
     if (!scroll) return
     const target = scroll.getChildren().find((child) => {
       return child.id === JSON.stringify(selected()?.value)