A macro command to mute error message for the next cast. Take care of muting the sound too.
Use /quietcast (/quiet or /qc) just before a /cast command to ignore its error.
# First try /cast SomeSpell # Do not report error if AnotherSpell fail /quietcast /cast AnotherSpell
Since v1.3 you pass a number of errors to ignore :
# First try /cast SomeSpell # Do not report error if AnotherSpell or YetAnotherSpell fail /qc 2 /cast AnotherSpell /cast YetAnotherSpell