[Bug] Potential fix for Expert Breeder's Pokemon being invisible

[PigeonBar]

What are the changes the user will see?

(Original bug report: https://discord.com/channels/1125469663833370665/1289869659297812520)

The Expert Pokemon Breeder's ace should never be invisible.

(Note: The linked bug report also mentioned some crashes when starting the Expert Pokemon Breeder. However, I was never able to reproduce a crash. So, I guess that this PR could also fix the crashes, but we can't know for sure.)

Why am I making these changes?

Fixing a bug, potentially fixing a crash.

What are the changes from a developer perspective?

The ME options for Expert Pokemon Breeder now properly return a Promise so that the game can wait for the Promise to be resolved before starting the battle. This Promise includes loading all assets needed for the battle, so this change should cause the game to wait for all assets to be loaded before starting the battle.

Also updated some tests.

How to test the changes?

Modify encounter-phase.utils.ts:340 to add a 5000ms delay to asset loading, like this:

loadEnemyAssets.push(new Promise(resolve => {
  setTimeout(() => {
    enemyPokemon.loadAssets().then(() => {
      resolve();
    });
  }, 5000);
}));

Also: npm run test expert-breeder

Screenshots/Videos

Before the changes:

20241014.Before.Breeder.Fix.mp4

After the changes:

20241014.After.Breeder.Fix.mp4

Checklist

• I'm using beta as my base branch
• There is no overlap with another PR?
• The PR is self-contained and cannot be split into smaller PRs?
• Have I provided a clear explanation of the changes?
• Have I considered writing automated tests for the issue?
• [ ] If I have text, did I make it translatable and add a key in the English locale file(s)?
• Have I tested the changes (manually)?
  • Are all unit tests still passing? (npm run test)
• Are the changes visual?
  • Have I provided screenshots/videos of the changes?

[DayKev]

Suggested change

	return scene.currentBattle?.enemyParty || [];
	return scene.currentBattle?.enemyParty ?? [];

[PigeonBar]

I used || instead of ?? because that's also the implementation of the original scene.getEnemyParty(), should it be changed there as well?

pokerogue/src/battle-scene.ts

Lines 791 to 793 in e962ac1

	getEnemyParty(): EnemyPokemon[] {
	return this.currentBattle?.enemyParty || [];
	}

[DayKev]

Suggested change

	return scene.currentBattle?.enemyParty || [];
	return scene.currentBattle?.enemyParty ?? [];

[DayKev]

Suggested change

	return scene.currentBattle?.enemyParty || [];
	return scene.currentBattle?.enemyParty ?? [];

[DayKev]

Tests currently override delays to be 1ms, might need to disable that for these tests. Lemme look into making some helper functions for that.

[PigeonBar]

inputs.test.ts also ultimately relies on setTimeout, so using setTimeout here should be fine.