check(PIEInstanceID != -1) assertion failed

[broly]

On 4.12 version this error occurs too.
I used next steps to reproduce error:

1. Created a new map TestLevel
2. Created a new second map LoginMap
3. Used as editor startup map is TestLevel
4. Used as Game default map is LoginMap
5. Used as Server default map is TestLevel
6. Created new GameInstance named MyGameInstance, and in StartGameInstance method used Engine->Browse(*WorldContext, URL, Error), where URL is parsed params from FCommandLine::Get().
7. Runs with dedicated server and without single process and with editor multiplayer mode: Play As Client (as on screenshot).

After this I logged URL and got next: