Player gets "connection lost, internal server error" when trying to join a server with mcda. Removing mcda (keeping mcdar and mcdw) fixes the problem.
Might be related to #42, but the server usually does not crash. When I try to rejoin many times it might crash, but I can't reproduce that anymore.

Server log when a player joins:
[15:58:08] [User Authenticator #1/INFO]: UUID of player 30_Salt is 00a2f34a-9834-4831-a852-948ee6124631 [15:58:09] [Server thread/INFO]: 30_Salt[/127.0.0.1:49276] logged in with entity id 367 at (-17.6767709691683, 84.0, 45.508177419438404) [15:58:09] [Server thread/INFO]: Server unpaused. [15:58:10] [Server thread/INFO]: 30_Salt joined the game [15:58:10] [Server thread/WARN]: @Redirect conflict. Skipping lithium.mixins.json:alloc.entity_tracker.EntityTrackerMixin->@Redirect::useFasterCollection()Ljava/util/Set; from mod lithium with priority 1000, already redirected by krypton.mixins.json:shared.network.microopt.TacsTrackedEntityMixin->@Redirect::construct$useFastutil()Ljava/util/Set; from mod krypton with priority 1000 [15:58:10] [Server thread/WARN]: Failed to handle packet for /127.0.0.1:49276 net.minecraft.class_148: Ticking player at Not Enough Crashes deobfuscated stack trace.(1.18.2+build.2) ~[?:?] at net.minecraft.server.network.ServerPlayerEntity.playerTick(ServerPlayerEntity:542) ~[?:?] at net.minecraft.server.network.ServerPlayNetworkHandler.tick(ServerPlayNetworkHandler:214) ~[?:?] at net.minecraft.network.ClientConnection.tick(ClientConnection:247) ~[?:?] at net.minecraft.server.ServerNetworkIo.tick(ServerNetworkIo:183) ~[?:?] at net.minecraft.server.MinecraftServer.handler$bmg000$onTickServer(MinecraftServer:7805) ~[server-intermediary.jar:?] at net.minecraft.server.MinecraftServer.tick(MinecraftServer) ~[server-intermediary.jar:?] at net.minecraft.server.MinecraftServer.runServer(MinecraftServer:697) ~[server-intermediary.jar:?] at net.minecraft.server.MinecraftServer.method_29739(MinecraftServer:273) ~[server-intermediary.jar:?] at java.lang.Thread.run(Thread.java:833) [?:?] Caused by: java.lang.ExceptionInInitializerError at chronosacaria.mcda.effects.ArmorEffects.<clinit>(ArmorEffects.java:49) ~[mcda-2.0.3.jar:?] at net.minecraft.entity.LivingEntity.handler$bif000$onMCDATickEffects(LivingEntity:12299) ~[?:?] at net.minecraft.entity.LivingEntity.tick(LivingEntity) ~[?:?] at net.minecraft.entity.player.PlayerEntity.tick(PlayerEntity:275) ~[?:?] at net.minecraft.server.network.ServerPlayerEntity.playerTick(ServerPlayerEntity:478) ~[?:?] ... 8 more Caused by: java.lang.IllegalStateException: Registry is already frozen at net.minecraft.util.registry.SimpleRegistry.createEntry(SimpleRegistry:343) ~[?:?] at net.minecraft.entity.EntityType.<init>(EntityType:155) ~[?:?] at net.fabricmc.fabric.impl.object.builder.FabricEntityType.<init>(FabricEntityType.java:31) ~[fabric-object-builder-api-v1-2.0+40c91ec860-692cd366897f99bd.jar:?] at net.fabricmc.fabric.api.object.builder.v1.entity.FabricEntityTypeBuilder.build(FabricEntityTypeBuilder.java:264) ~[fabric-object-builder-api-v1-2.0+40c91ec860-692cd366897f99bd.jar:?] at chronosacaria.mcda.registry.SummonedEntityRegistry.<clinit>(SummonedEntityRegistry.java:27) ~[mcda-2.0.3.jar:?] at chronosacaria.mcda.effects.ArmorEffects.<clinit>(ArmorEffects.java:49) ~[mcda-2.0.3.jar:?] at net.minecraft.entity.LivingEntity.handler$bif000$onMCDATickEffects(LivingEntity:12299) ~[?:?] at net.minecraft.entity.LivingEntity.tick(LivingEntity) ~[?:?] at net.minecraft.entity.player.PlayerEntity.tick(PlayerEntity:275) ~[?:?] at net.minecraft.server.network.ServerPlayerEntity.playerTick(ServerPlayerEntity:478) ~[?:?] ... 8 more [15:58:10] [Netty Server IO #1/INFO]: Server paused. [15:58:10] [Server thread/INFO]: 30_Salt lost connection: Internal server error [15:58:10] [Server thread/INFO]: 30_Salt left the game [15:58:10] [Server thread/INFO]: Disconnecting client 30_Salt