Up until now, the `UserActivity` class hierarchy contained things like
beatmap info, room info, full replay info, etc. While this was
convenient, it is soon going to be less so, as the data is sent over the
wire to the spectator server so that the user's activity can be
broadcast to other clients.
To counteract this without creating a second separate and slimmed-down
class hierarchy, slim down the `UserActivity` structure to contain the
bare minimum amounts of data such that the structures aren't overly
large and complex to serialise, but also contain enough data that they
can be used by receiving clients directly without having to do beatmap
or score lookups.
Closes#25663 (again).
As it turns out, in some scenarios it can be the case that the current
game-global `Beatmap` is not valid for the current game-global
`Ruleset`. The validity of one and the other in conjunction is only
really validated by the song select screen; elsewhere there is no
guarantee that the global beatmap is playable using the global ruleset.
However, this only comes up in very specific circumstances, namely one:
when trying to autoplay a catch beatmap with osu! ruleset globally
active via the skin editor flow.
`Player` is responsible for retrieving the beatmap to be played. It does
so by invoking the appropriate beatmap converter and asking it if the
beatmap can be converted:
6d64538d7a/osu.Game/Beatmaps/WorkingBeatmap.cs (L262-L266)
If the code above throws, `Player` actually silently covers for this, by
trying the beatmap's default ruleset instead:
6d64538d7a/osu.Game/Screens/Play/Player.cs (L529-L536)
However, for the pairing of osu! ruleset and catch beatmap, this fails,
as `OsuBeatmapConverter`'s condition necessary for permitting conversion
is that the objects have a defined position:
6d64538d7a/osu.Game.Rulesets.Osu/Beatmaps/OsuBeatmapConverter.cs (L25)
which they will do, due to the fact that all catch beatmaps are really
just osu! beatmaps but with conversion steps applied, and thus `Player`
succeeds to load the catch beatmap in osu! ruleset.
In the skin editor scenario, this would lead to the secondary failure
of the skin editor trying to apply `CatchModAutoplay` on top of all
of that, which would fail at the hard-cast of the beatmap
to `CatchBeatmap`.
