One Mia here to assist!
Go to character configuration theeen > log window settings at very bottom > in general tab unselect these two options
"Display error messages when actions fail."
"Display recast time error messages."
You may also wish to disable the "Your mount can fly no higher" message here!
"Disable altitude error messages."
Uncertain why this is in logs and not elsewhere, it is most confusing.
Be sure to test in combat only! It will still produce the error bleep beep sound if you spam buttons out of combat.