death message: a creeper's blast names the creeper, not the last mob that hit

The creeper is out of the mob list when its blast lands, so its name now comes with the explosion event. Fixes #2978.

crates/horizon-client/src/game/creatures.rs

@@ -1193,14 +1193,18 @@ impl Game<'_> {
                     owner,
                 } => self.add_fangs(at, yaw, delay, owner),
                 MobEvent::Shoot(..) => {}
-                MobEvent::ExplosionSource { mob, charged } => {
+                MobEvent::ExplosionSource { mob, charged, name } => {
                     self.combat.explosion_source = Some(mob);
+                    // The creeper causes the blast's damage, but it is out of
+                    // the mob list already: its name comes with the event.
+                    self.note_named_attacker("minecraft:explosion", mob, name);
                     if charged {
                         self.combat.charged_exploders.push(mob);
                     }
                 }
                 MobEvent::Explode(at, radius, species) => {
                     // The exploding mob causes the damage (Creeper.explodeCreeper).
+                    let noted = self.combat.explosion_source.is_some();
                     let source_mob = self.combat.explosion_source.or_else(|| {
                         self.mobs
                             .iter()
@@ -1211,7 +1215,7 @@ impl Game<'_> {
                             .map(|m| m.id)
                             .next()
                     });
-                    if let Some(id) = source_mob {
+                    if !noted && let Some(id) = source_mob {
                         self.note_attacker("minecraft:explosion", id);
                     }
                     self.combat.explosion_source = source_mob;

crates/horizon-client/src/mobs.rs

@@ -1108,10 +1108,12 @@ pub enum MobEvent {
     /// The mob the `Explode` right after this comes from
     /// (`ServerExplosion.source`), and whether it is a charged creeper: the
     /// exploding creeper is already out of the mob list when the game applies
-    /// the blast, so its victims' loot cannot look it up.
+    /// the blast, so its victims' loot cannot look it up, nor the death
+    /// message its name (`name`, `getDisplayName`).
     ExplosionSource {
         mob: u32,
         charged: bool,
+        name: crate::text::Text,
     },
     /// The centre, the radius and the kind of the mob blowing up (it may be
     /// gone from the list by the time the blast is handled).

crates/horizon-client/src/mobs/hostile.rs

@@ -326,9 +326,17 @@ pub fn creeper_tick(m: &mut Mob, events: &mut Vec<MobEvent>) {
     if m.swell >= 30 {
         m.swell = 30;
         let radius = if m.extra.charged { 6.0 } else { 3.0 };
+        let name = match &m.custom_name {
+            Some(name) => crate::text::Text::literal(name.clone()),
+            None => crate::text::Text::translate(
+                &format!("entity.{}", m.kind.id.replace(':', ".")),
+                &[],
+            ),
+        };
         events.push(MobEvent::ExplosionSource {
             mob: m.id,
             charged: m.extra.charged,
+            name,
         });
         events.push(MobEvent::Explode(
             [m.position.x, m.position.y, m.position.z],