在 Reason 字段（徽章）中添加外部链接会静默失败

[saurabhp (Saurabh Patel)]

Hi @dax ,
I have created PR for the same. I just wanted to confirm only links have to be allowed in reason, right? Plain text is also not valid, right?

FIX: throw error when link in reason for grant badge is an external link

Thanks