Fix Crashes when Sprites for Pokémon are missing (#1021)

* Fix Crashes when Sprites for Pokémon are missing

Fixes an issue where a missing sprite will cause the game to crash instead of using the base sprite or the Substitute sprite.

Failsafes were already in place to load these backups, this code just allows a graceful fail and a simple error message instead of a crash.

* Check Against OK status

src/field/pokemon.ts

@@ -329,7 +329,15 @@ export default abstract class Pokemon extends Phaser.GameObjects.Container {
                   if (variantSet && variantSet[this.variant] === 1) {
                     if (variantColorCache.hasOwnProperty(key))
                       return resolve();
-                    this.scene.cachedFetch(`./images/pokemon/variant/${useExpSprite ? 'exp/' : ''}${battleSpritePath}.json`).then(res => res.json()).then(c => {
+                    this.scene.cachedFetch(`./images/pokemon/variant/${useExpSprite ? 'exp/' : ''}${battleSpritePath}.json`).
+                      then(res => {
+                        // Prevent the JSON from processing if it failed to load
+                        if (!res.ok) {
+                          console.error(`Could not load ${res.url}!`);
+                          return;
+                        }
+                        res.json()
+                      }).then(c => {
                           variantColorCache[key] = c;
                           resolve();
                     });
@@ -493,9 +501,31 @@ export default abstract class Pokemon extends Phaser.GameObjects.Container {
     this.shinySparkle = shinySparkle;
   }
 
+  /**
+   * Attempts to animate a given {@linkcode Phaser.GameObjects.Sprite}
+   * @see {@linkcode Phaser.GameObjects.Sprite.play}
+   * @param sprite {@linkcode Phaser.GameObjects.Sprite} to animate
+   * @param tintSprite {@linkcode Phaser.GameObjects.Sprite} placed on top of the sprite to add a color tint
+   * @param animConfig {@linkcode String} to pass to {@linkcode Phaser.GameObjects.Sprite.play}
+   * @returns true if the sprite was able to be animated
+   */
+  tryPlaySprite(sprite: Phaser.GameObjects.Sprite, tintSprite: Phaser.GameObjects.Sprite, key: string): boolean {
+    // Catch errors when trying to play an animation that doesn't exist
+    try {
+      sprite.play(key);
+      tintSprite.play(key);
+    }
+    catch(error: unknown) {
+      console.error(`Couldn't play animation for '${key}'!\nIs the image for this Pokemon missing?\n`, error);
+
+      return false;
+    }
+
+    return true;      
+  }
+  
   playAnim(): void {
-    this.getSprite().play(this.getBattleSpriteKey());
-    this.getTintSprite().play(this.getBattleSpriteKey());
+    this.tryPlaySprite(this.getSprite(), this.getTintSprite(), this.getBattleSpriteKey());
   }
 
   getFieldPositionOffset(): [ number, number ] {