refactor(persons): replace non-null assertion with null guard on removeFormEl

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/routes/persons/[id]/edit/NameHistoryEditCard.svelte

@@ -43,9 +43,9 @@ async function handleDelete(id: string) {
 		body: m.person_alias_delete_body(),
 		destructive: true
 	});
-	if (confirmed) {
+	if (confirmed && removeFormEl) {
 		if (aliasIdInputEl) aliasIdInputEl.value = id;
-		removeFormEl!.requestSubmit();
+		removeFormEl.requestSubmit();
 	}
 }
 </script>