AppSync VTL 解析程序 - 如何解决分析错误

问：

我在 VTL 响应映射上收到此错误，但不确定这意味着什么

graphql: Encountered "}" at velocity[line 9, column 3]
                                Was expecting one of:
                                    "[" ...
                                    "{" ...
                                    <STRING_LITERAL> ...
                                    "true" ...
                                    "false" ...
                                    <INTEGER_LITERAL> ...
                                    <FLOATING_POINT_LITERAL> ...
                                    <IDENTIFIER> ...
                                    "{" ...
                                    "[" ...

对于以下响应映射：

#set($isAdmin = $ctx.identity.resolverContext.is_admin)

#if(!$isAdmin)
  $util.toJson({
    "availability": {
      "startsAt": $ctx.result.availability.startsAt,
      "endsAt": $ctx.result.availability.endsAt,
    }
  })
#end

$util.toJson($ctx.result)