1.8.8: NoSuchElementException in boss bar

[kangarko]

Got the following sentry report:

java.util.NoSuchElementException: null
    at java.util.concurrent.CopyOnWriteArrayList$COWIterator.next(CopyOnWriteArrayList.java:1157)
    at net.kyori.adventure.platform.bukkit.CraftBukkitFacet$BossBarWither.<init>(CraftBukkitFacet.java:1401)
    at net.kyori.adventure.platform.bukkit.CraftBukkitFacet$BossBarWither.<init>(CraftBukkitFacet.java:1385)
    at net.kyori.adventure.platform.bukkit.CraftBukkitFacet$BossBarWither$Builder.createBossBar(CraftBukkitFacet.java:1394)
    at net.kyori.adventure.platform.bukkit.CraftBukkitFacet$BossBarWither$Builder.createBossBar(CraftBukkitFacet.java:1386)
    at net.kyori.adventure.platform.facet.FacetAudience.showBossBar(FacetAudience.java:406)
    at net.kyori.adventure.platform.bukkit.BukkitAudience.showBossBar(BukkitAudience.java:107)
    at org.mineacademy.corearena.lib.platform.BukkitPlayer.showBossBar0(BukkitPlayer.java:312)
    at org.mineacademy.corearena.lib.platform.BossBarTask.show(BossBarTask.java:85)
    at org.mineacademy.corearena.lib.platform.FoundationPlayer.showBossBar(FoundationPlayer.java:700)
    at org.mineacademy.corearena.lib.platform.FoundationPlayer.showBossBar(FoundationPlayer.java:715)
    at org.mineacademy.corearena.lib.platform.FoundationPlayer.showBossBar(FoundationPlayer.java:733)
    at org.mineacademy.corearena.impl.SimpleBossBarLegacy.updateSingle(SimpleBossBarLegacy.java:34)
    at org.mineacademy.corearena.impl.SimpleBossBarLegacy.update(SimpleBossBarLegacy.java:30)
    at org.mineacademy.corearena.impl.SimpleBossBarLegacy.updateProgress(SimpleBossBarLegacy.java:48)
    at org.mineacademy.corearena.impl.SimplePhaseIncremental.onTimerTick(SimplePhaseIncremental.java:122)
    at org.mineacademy.corearena.countdown.PhaseCountdown.onTick(PhaseCountdown.java:35)
    at org.mineacademy.corearena.lib.model.Countdown.run(Countdown.java:75)
    at org.mineacademy.corearena.lib.CommonCore.lambda$wrapRunnableInExceptionCatcher$6(CommonCore.java:1801)
    at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftTask.run(CraftTask.java:59)
    at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:352)
    at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:783)
    at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:378)
    at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:713)
    at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:616)
    at java.lang.Thread.run(Thread.java:748)

Environment: 1.8.8-R0.1-SNAPSHOT, CraftBukkit

Thanks.