Rescinded 3pid invites show as errors

[pixlwave]

Original report in element-hq/element-x-ios#5795

Steps to reproduce

• Alice sends a 3pid invite to charlie@example.com via EW
• Bob revokes the invite in EW
• Bob sees the following in EX:

Outcome

What did you expect?

No choking on rescinded 3PIDs

What happened instead?

It choked on this:

{
  "unsigned": {
    "replaces_state": "$66JyLdjku41oL48JN1eUM-WfZIgAWeCIisWCNeeo7vY",
    "prev_content": {
      "display_name": "c...@u...",
      "key_validity_url": "https://vector.im/_matrix/identity/v2/pubkey/isvalid",
      "public_key": "ta8IQ0u1sp44HVpxYi7dFOdS/bfwDjcy4xLFlfY5KOA",
      "public_keys": [
        {
          "key_validity_url": "https://vector.im/_matrix/identity/api/v1/pubkey/isvalid",
          "public_key": "ta8IQ0u1sp44HVpxYi7dFOdS/bfwDjcy4xLFlfY5KOA"
        },
        {
          "key_validity_url": "https://vector.im/_matrix/identity/api/v1/pubkey/ephemeral/isvalid",
          "public_key": "MdzMaOKonWpBri_6V8_ZymM6l7qhhc1MuhvgF6F43ms"
        }
      ]
    },
    "prev_sender": "@raherne:matrix.org",
    "age": 742,
    "membership": "join"
  },
  "content": {},
  "origin_server_ts": 1782410538742,
  "sender": "@matthew:matrix.org",
  "state_key": "qzKknoYicpbkGBckNvNqfboCQhCOXHGzUEztJGcKwRneghxNsamUvgHuNkdRsILELNybekRrnoQGWONQxOsEcadXtozixbHcBixfpiYSVerolNEVWIHsENxDlyNPmcST",
  "type": "m.room.third_party_invite",
  "event_id": "$kUdQvLsBiKYEiUDs_noXUk6w6419U1EXx-aNL44uExg",
  "room_id": "!somewhere:matrix.org"
}

Your phone model

macOS

Operating system version

No response

Application version

1252

Homeserver

matrix.org

Will you send logs?

No