Error due to specifying an unknown language for EVAL
is Exception
Error thrown when EVAL($str, :$lang)
specifies a language that the compiler does not know how to handle.
For example
EVAL 'boo', lang => "bar";CATCH ;# OUTPUT: «X::Eval::NoSuchLang: No compiler available for language 'bar'»
method lang()
Returns the language that EVAL did not know how to handle.