Fix eask-test-ert--message breaks tests which trigger minibuffer

[joshbax189]

From the doco: (message nil) can be used to clear the minibuffer.

However, eask-test-ert--message is advised on message when running eask test ert and passes all message args to format, which requires a format string.

The provided test incorrectly fails with a signal (it should succeed)

(ert-deftest ert-test-1 ()
  (should-not (message nil)))

The backtrace is like

Test ert-test-1 backtrace:
  format(nil)
  apply(format nil)
  (string-match-p "^[ ]+FAILED " (apply #'format args))
  (cond ((string-match-p "^[ ]+FAILED " (apply #'format args)) (eask-m
  (let ((eask-test-ert--message-loop t)) (cond ((string-match-p "^[ ]+
  (if eask-test-ert--message-loop (apply fnc args) (let ((eask-test-er
  eask-test-ert--message(#<subr message> nil)
  apply(eask-test-ert--message #<subr message> nil)
  message(nil)
  apply(message nil)
...

Fixed by passing the nil argument to message. This does not appear to create extra messages in Eask output.

[jcs090218]

Some nits. Most look good to me! 🚀

[jcs090218]

Thank you!