Bug: Unable to join a friend's game by invitation

[kostaleks]

Summary

It is impossible to accept an invitation to a game
requirement: |
The user can accept the invitation to play
prerequisites: |
User is authorized
The user received an invitation from another player
test-data: |
no-data

Current version: c655ad4

Баг был открыт ранее, но уже закрыт: 2047

Reproduction steps

1. Click on the invite
2. Click accept

Expected result

The game begins

Actual result

Error 500. The game doesn't begin

Browsers

Chrome

OS

Windows