500 Error when creating a stripe account when less than 13 years old

# Problem

When, through the donation feature, attempting to create a Stripe account for someone who is less than 13 years old, a 500 error is rendered, due to the case not being handled properly.

## Subtasks

- Create and solve API issue to send a specific response for this error case
- Handle that API response properly in Ember as part of this issue

从 Ember 中捐赠功能的 Stripe 账户创建流程开始，追踪针对 13 岁以下用户的 API 响应。协调 API 响应的更改，在 Ember 中处理该响应，并验证 500 情况已被具体响应替代。

由索引模型根据 Issue 内容生成。