Debugger entered--Lisp error: (wrong-type-argument char-or-string-p nil)
  describe-package-1(#s(package-desc :name matlab-mode :version (20180928 1526) :summary "Major mode for MATLAB(R) dot-m files" :reqs nil :kind nil :archive nil :dir "/home/oub/.emacs.d/elpa/matlab-mode-20180928.1526" :extras ((:keywords "matlab" "programming" "language" "(X)emacs") (:url . "http://sourceforge.net/projects/matlab-emacs/")) :signed nil))
  describe-package(#s(package-desc :name matlab-mode :version (20180928 1526) :summary "Major mode for MATLAB(R) dot-m files" :reqs nil :kind nil :archive nil :dir "/home/oub/.emacs.d/elpa/matlab-mode-20180928.1526" :extras ((:keywords "matlab" "programming" "language" "(X)emacs") (:url . "http://sourceforge.net/projects/matlab-emacs/")) :signed nil))
  package-menu-describe-package()
  funcall-interactively(package-menu-describe-package)
  call-interactively(package-menu-describe-package nil nil)
  command-execute(package-menu-describe-package)