1.7 clients crashing when loading the Bossbar

[Stualyttle]

My 1.7 clients are crashing when they are loading the Bossbar. The Whitherskull is chashing them.
Could there be a option to disable it for 1.7 users only?

Thank you!

[Gerrygames]

Could you provide the crash log?

[Stualyttle]

The error is the same for both 1.7.2 and 1.7.10 I've used 1.7.10 and I've added a gif, a pasted the error (verry short xP) And the long error.

GIF:

Short:
The game crashed whilst ticking entity
Error: java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Byte

Full: https://pastebin.com/NSVqZtkN