module T::Private::ErrorHandler

def self.handle_call_validation_error(signature, opts={})

is unset, this method will call handle_call_validation_error_default.
behavior when a sig call fails. If T::Configuration.call_validation_error_handler
Handle a sig call validation failure. This allows users to override the 
def self.handle_call_validation_error(signature, opts={})
  T::Configuration.call_validation_error_handler(signature, opts)
  nil
end