User Search can't find user with unicode top level domain

Neither of these find the user:

• @payphone@zetsubou.xn--q9jyb4c
• @payphone@zetsubou.みんな
• payphone@zetsubou.xn--q9jyb4c
• payphone@zetsubou.みんな
• https://zetsubou.xn--q9jyb4c/payphone

Backend returns errors: {detail: "Internal server error"}

(Moved from pleroma-fe#582 (closed))