well it does not work not sure why
but the !aspect one does something i like i didnt know i could use ! in that manner
Also

#showtooltip
/console Sound_EnableSFX 0
/cast !Aspect of the Viper
/console Sound_EnableSFX 1
/script UIErrorsFrame:Clear()

Does not disable sound and re enable
However its not necessary because

/cast !Aspect of the Viper

causes no error at all no need to clear error frame or disable sound