Fix exception when telepad system plays beam animations

[eoineoineoin]

About the PR

Fixes an exception raised when an order was sent to a cargo telepad.

Why / Balance

Less runtime errors, please.

Technical details

Content.Client.Cargo.Systems.CargoSystem.OnChangeData was reentrant, but did not handle this correctly.

When the appearancechanged event was raised, sending the component into a CargoTelepadState.Teleporting state, the code previously:

1. Checked if TelepadBeamKey was playing, and if so, early-out
2. Stop playing TelepadIdleKey
3. Play TelepadBeamKey

However, inside step 2, an AnimationCompletedEvent is raised, which calls OnChangeData() again (i.e. running steps 1-3). When that completes and we attempt to execute 3, the animation is already playing, raising an exception because the early-out in step 1 was invalidated:

[DEBG] root: Switching to state Content.Client.Gameplay.GameplayState
Unhandled exception. System.ArgumentException: An item with the same key has already been added. Key: cargo-telepad-beam
   at System.Collections.Generic.Dictionary`2.TryInsert(TKey key, TValue value, InsertionBehavior behavior)
   at System.Collections.Generic.Dictionary`2.Add(TKey key, TValue value)
   at Robust.Client.GameObjects.AnimationPlayerSystem.Play(Entity`1 ent, Animation animation, String key) in /home/eoin/code/space-station-14/RobustToolbox/Robust.Client/GameObjects/EntitySystems/AnimationPlayerSystem.cs:line 154
   at Robust.Client.GameObjects.AnimationPlayerSystem.Play(EntityUid uid, AnimationPlayerComponent component, Animation animation, String key) in /home/eoin/code/space-station-14/RobustToolbox/Robust.Client/GameObjects/EntitySystems/AnimationPlayerSystem.cs:line 99
   at Content.Client.Cargo.Systems.CargoSystem.OnChangeData(EntityUid uid, SpriteComponent sprite) in /home/eoin/code/space-station-14/Content.Client/Cargo/Systems/CargoSystem.Telepad.cs:line 79
   at Content.Client.Cargo.Systems.CargoSystem.OnCargoAppChange(EntityUid uid, CargoTelepadComponent component, AppearanceChangeEvent& args) in /home/eoin/code/space-station-14/Content.Client/Cargo/Systems/CargoSystem.Telepad.cs:line 57
   at Robust.Shared.GameObjects.EntityEventBus.<>c__DisplayClass56_0`2.<SubscribeLocalEvent>g__EventHandler|0(EntityUid uid, IComponent comp, TEvent& args) in /home/eoin/code/space-station-14/RobustToolbox/Robust.Shared/GameObjects/EntityEventBus.Directed.cs:line 305

Media

Requirements

• I have read and am following the Pull Request and Changelog Guidelines.
• I have added media to this PR or it does not require an ingame showcase.

Breaking changes

Changelog