Improve warning and error messages

* lisp/emacs-lisp/eieio-base.el (eieio-persistent-read,
  (eieio-persistent-validate/fix-slot-value): Indicate exactly what
  went wrong.
latest
Status Job ID Name Coverage
  Test
failed #14
test

 
Name Stage Failure
failed
test Test There has been a timeout failure or the job got stuck. Check your timeout limits or try again
No job log