the missing sounds appear in the log after you close the game

Completely ignored arguments: [--nativeLauncherVersion, 286]
[08:53:08] [Client thread/INFO]: Setting user: NicosaurusRex99

[08:53:10] [Client thread/INFO]: LWJGL Version: 2.9.4
[08:53:10] [Client thread/INFO]: Reloading ResourceManager: Default
[08:53:11] [Client thread/WARN]: Missing sound for event: minecraft:enchant.thorns.hit
[08:53:11] [Client thread/WARN]: Missing sound for event: minecraft:entity.guardian.thorns
[08:53:11] [Client thread/WARN]: Missing sound for event: minecraft:entity.horse.eat
[08:53:11] [Client thread/WARN]: Missing sound for event: minecraft:entity.rabbit.attack
[08:53:11] [Sound Library Loader/INFO]: Starting up SoundSystem...
[08:53:11] [Thread-5/INFO]: Initializing LWJGL OpenAL
[08:53:11] [Thread-5/INFO]: (The LWJGL binding of OpenAL. For more information, see http://www.lwjgl.org)
[08:53:11] [Thread-5/INFO]: OpenAL initialized.
[08:53:12] [Sound Library Loader/INFO]: Sound engine started
[08:53:13] [Client thread/INFO]: Created: 1024x512 textures-atlas
[08:53:16] [Client thread/INFO]: Stopping!
[08:53:17] [Client thread/INFO]: SoundSystem shutting down...
[08:53:17] [Client thread/WARN]: Author: Paul Lamb, www.paulscode.com