Fatal Error When Trying to Play Custom Music

When playing my custom music, it seems like it throws an error and fails to play the song.
This is the error given upon playing a custom song:

[23:56:57] [Server thread/INFO]: [RobuxShooters: Played sound 'custom.ballad' to RobuxShooters]
[23:56:58] [Client thread/FATAL]: Error executing task
java.util.concurrent.ExecutionException: java.lang.NullPointerException
	at java.util.concurrent.FutureTask.report(Unknown Source) ~[?:1.8.0_111]
	at java.util.concurrent.FutureTask.get(Unknown Source) ~[?:1.8.0_111]
	at h.a(SourceFile:47) [17w16b.jar:?]
	at bgz.ax(SourceFile:956) [17w16b.jar:?]
	at bgz.a(SourceFile:404) [17w16b.jar:?]
	at net.minecraft.client.main.Main.main(SourceFile:123) [17w16b.jar:?]
Caused by: java.lang.NullPointerException
	at cfk.a(SourceFile:34) ~[17w16b.jar:?]
	at cgi.c(SourceFile:305) ~[17w16b.jar:?]
	at cgk.a(SourceFile:195) ~[17w16b.jar:?]
	at bra.a(SourceFile:1387) ~[17w16b.jar:?]
	at ie.a(SourceFile:90) ~[17w16b.jar:?]
	at ie.a(SourceFile:10) ~[17w16b.jar:?]
	at hd$1.run(SourceFile:13) ~[17w16b.jar:?]
	at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) ~[?:1.8.0_111]
	at java.util.concurrent.FutureTask.run(Unknown Source) ~[?:1.8.0_111]
	at h.a(SourceFile:46) ~[17w16b.jar:?]
	... 3 more
[23:56:58] [Client thread/INFO]: [CHAT] Played sound 'custom.ballad' to RobuxShooters

I'll also provide the directories I placed my files in.

resources.zip:
AppData\Roaming\.minecraft\saves*FILENAME*\resources.zip
pack.mcmeta:
resources.zip\pack.mcmeta
sounds.json:
resources.zip\assets\minecraft
music:
resources.zip\assets\minecraft\sounds\custom

I know that my file ran smoothly before since I tried it in, I think, 1.8 or so. I even changed the "pack_format" to 3. Is it that you are supposed to put the "resources.zip" somewhere instead of the world save folder? But an error is still an error unless I have done something wrong somewhere. I also want the music to come along with the map, not a seperate resource pack. Is this something that changed and I am not aware of it?