Since #7786, the GUI tick completed normally after calling
`closePageCallback` instead of being cancelled like previously. Since
`Engine.EndGame` deletes the internal `g_Game` pointer, every Engine call
after it that tried to access `g_Game` caused a segfault.
This patch solves it by moving `Engine.EndGame` to the very end, right
before closing the session page.
In order to follow the convention that only functions directly closing
the page are called `closePageCallback`, that function is in turn
renamed to `closeSession`. Additionally, this allows only resolving
the promise with a bool (`showSummary`) and then only calling
`getNextPageOpenRequest` at the end of `init` for reasons of simplicity.
After 78900842b1, the following message was shown to clients when the
host disconnected during game setup:
"Lost connection to the server.
[Invalid value undefined]"
This patch fixes that.
Allows devs (and players) to skip the summary page when they don't need
them.
Patch by: @Schweini
Differential revision: https://code.wildfiregames.com/D3958
Reviewed by: @Langbart
Fixes: #4300
Comments by: @nwtour, @Stan
This was SVN commit r25978.