Why is this paragraph spamming my game output?

Recently, I checked my logs and looked for some evidence to punish a player on another server, and I realised that my game output is constantly flooded with this particular paragraph:

[22:17:17] [Client thread/FATAL]: Error executing task
java.util.concurrent.ExecutionException: java.lang.IllegalArgumentException: Default value cannot be lower than minimum value!
     at java.util.concurrent.FutureTask$Sync.innerGet(FutureTask.java:222) ~[?:1.6.0_65]
     at java.util.concurrent.FutureTask.get(FutureTask.java:83) ~[?:1.6.0_65]
     at h.a(SourceFile:61) [h.class:?]
     at avf.av(SourceFile:880) [avf.class:?]
     at avf.a(SourceFile:325) [avf.class:?]
     at net.minecraft.client.main.Main.main(SourceFile:124) [Main.class:?]
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.6.0_65]
     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) ~[?:1.6.0_65]
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) ~[?:1.6.0_65]
     at java.lang.reflect.Method.invoke(Method.java:597) ~[?:1.6.0_65]
     at net.minecraft.launchwrapper.Launch.launch(Launch.java:131) [launchwrapper-1.7.jar:?]
     at net.minecraft.launchwrapper.Launch.main(Launch.java:27) [launchwrapper-1.7.jar:?]
Caused by: java.lang.IllegalArgumentException: Default value cannot be lower than minimum value!
     at qk.<init>(SourceFile:21) ~[qk.class:?]
     at bcz.a(SourceFile:1442) ~[bcz.class:?]
     at ib.a(SourceFile:70) ~[ib.class:?]
     at ib.a(SourceFile:15) ~[ib.class:?]
     at fi$1.run(SourceFile:13) ~[fi$1.class:?]
     at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:439) ~[?:1.6.0_65]
     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303) ~[?:1.6.0_65]
     at java.util.concurrent.FutureTask.run(FutureTask.java:138) ~[?:1.6.0_65]
     at h.a(SourceFile:60) ~[h.class:?]
     ... 9 more

This makes my output complete unreadable and prevents me from doing something I want to do.

I suspect that it is caused by the server I usually play on because this only happens when I am playing on that server.

Why is this happening? What does these lines mean? Is there any way that I can do to fix it?