After accepting a TPA from another player the client crashes to desktop. All of Fabric 3 server.

[00:28:21] [main/FATAL]: Unreported exception thrown!
java.lang.ClassCastException: net.minecraft.text.LiteralText cannot be cast to net.minecraft.text.TranslatableText
at net.minecraft.client.gui.hud.BossBarHud.handler$bgl000$renderCustomBossBar(BossBarHud.java:532) ~[intermediary-1.16.4.jar:?]
at net.minecraft.client.gui.hud.BossBarHud.renderBossBar(BossBarHud.java) ~[intermediary-1.16.4.jar:?]
at net.minecraft.client.gui.hud.BossBarHud.render(BossBarHud.java:44) ~[intermediary-1.16.4.jar:?]
at net.minecraft.client.gui.hud.InGameHud.render(InGameHud.java:208) ~[intermediary-1.16.4.jar:?]
at net.minecraft.client.render.GameRenderer.render(GameRenderer.java:597) ~[intermediary-1.16.4.jar:?]
at net.minecraft.client.MinecraftClient.render(MinecraftClient.java:1048) ~[intermediary-1.16.4.jar:?]
at net.minecraft.client.MinecraftClient.run(MinecraftClient.java:681) [intermediary-1.16.4.jar:?]
at net.minecraft.client.main.Main.main(Main.java:215) [intermediary-1.16.4.jar:?]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_242]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_242]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_242]
at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_242]
at net.fabricmc.loader.game.MinecraftGameProvider.launch(MinecraftGameProvider.java:224) [fabric-loader-0.10.8.jar:?]
at net.fabricmc.loader.launch.knot.Knot.init(Knot.java:141) [fabric-loader-0.10.8.jar:?]
at net.fabricmc.loader.launch.knot.KnotClient.main(KnotClient.java:27) [fabric-loader-0.10.8.jar:?]

I managed to reproduce only once; If it happens every time for you, can you give more specifics, like client mods, client (fabric) versions, server Fabric API version and server mods?

https://www.curseforge.com/minecraft/modpacks/all-of-fabric-3/files/3133172 All of Fabric 3 v2.5.2 modpack. Minecraft 1.16.4. It happens every time to the person being teleported. Hoping to add it to the public servers since GunPowder has not been maintained.

Okay this is really puzzling me, LiteralText and TranslatableText should be basically interchangeable. It could be that one of the other 140+ mods changes some functionality of the CommandBossBar, but i really don't want to try to find out which one...

If i can't find the cause/a solution, would a temporary one be okay? I'm thinking a gamerule/connfig that allows to bypass the boss bar, and use some other method for the countdown.

Should be fixed on battle-towers side with v3.3.0
Draylar/battle-towers#35 (comment)

I probably should have grabbed the crash log. forgot I also have useful things like mixintrace. Here is the crash log. https://hastebin.com/idojumulac.yaml and here is the list of BossBarHud Mixins. Much smaller lol. :) But yes a toggle for not using the boss bar would also work.
Mixins in Stacktrace:
net.minecraft.class_337:
draylar.battletowers.mixin.BossBarHudMixin (battletowers.mixins.json)
com.github.chainmailstudios.astromine.mixin.BossBarHudMixin (astromine.mixins.json)

Thanks to the extra info you've given, I have found that the incompatible mod is Battle Towers, and I've submitted an issue regarding this (Draylar/battle-towers#35).
Meanwhile I'll release update 1.3.0, adding a config and an option to disable the BossBar.

Leaving this issue open while Draylar/battle-towers#35 is not solved.

Just thought I would let you know, that Battle Towers was causing the same client crash after someone named a wither on AoF3 NA server causing anyone going into the End to crash as well haha.