Fix server crash on 1.17

[Toshimichi0915]

Leaving the server without completing the captcha will result in server crash in 1.17.1(both paper/spigot)
This PR fixes that issue.

[haq]

Leaving the server without completing the captcha will result in server crash in 1.17.1(both paper/spigot) This PR fixes that issue.

I am unable to get my 1.17.1 server to crash, can you provide a crash log?

[Toshimichi0915]

Crash log

java.util.ConcurrentModificationException
	at java.base/java.util.ArrayList$Itr.checkForComodification(ArrayList.java:1013)
	at java.base/java.util.ArrayList$Itr.next(ArrayList.java:967)
	at org.bukkit.craftbukkit.v1_17_R1.map.CraftMapView.render(CraftMapView.java:150)
	at app//net.minecraft.world.level.saveddata.maps.MapItemSavedData$HoldingPlayer.nextUpdatePacket(MapItemSavedData.java:630)
	at app//net.minecraft.world.level.saveddata.maps.MapItemSavedData.getUpdatePacket(MapItemSavedData.java:434)
	at app//net.minecraft.world.item.MapItem.getUpdatePacket(MapItem.java:370)
	at app//net.minecraft.server.level.ServerPlayer.doTick(ServerPlayer.java:679)
	at app//net.minecraft.server.players.PlayerList.disconnect(PlayerList.java:610)
	at app//net.minecraft.server.players.PlayerList.disconnect(PlayerList.java:592)
	at app//net.minecraft.server.network.ServerGamePacketListenerImpl.onDisconnect(ServerGamePacketListenerImpl.java:1967)
	at app//net.minecraft.server.network.ServerGamePacketListenerImpl.onDisconnect(ServerGamePacketListenerImpl.java:1947)
	at app//net.minecraft.network.Connection.handleDisconnection(Connection.java:743)
	at app//net.minecraft.server.network.ServerConnectionListener.tick(ServerConnectionListener.java:221)
	at app//net.minecraft.server.MinecraftServer.tickChildren(MinecraftServer.java:1654)
	at app//net.minecraft.server.dedicated.DedicatedServer.tickChildren(DedicatedServer.java:490)
	at app//net.minecraft.server.MinecraftServer.tickServer(MinecraftServer.java:1481)
	at app//net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1280)
	at app//net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:319)
	at java.base/java.lang.Thread.run(Thread.java:831)

Paper org.bukkit.craftbukkit.map.CraftMapView line 159

150|        for (MapRenderer renderer : this.renderers) {
___|            ...
158|            try {
159|                renderer.render(this, canvas, player);
160|            } catch (Throwable ex) {
161|                Bukkit.getLogger().log(Level.SEVERE, "Could not render map using renderer " + renderer.getClass().getName(), ex);
162|            }
___|            ...
___|        }

Removing a renderer on render method will cause ConcurrentModificationException. I'm not sure why the server didn't crash in your case, though.