Subject: 27.0.50; enriched-mode cannot save anonymous faces

From: [email-masked] (Charles A. Roelli)
Date: Sun, 09 Dec 2018 11:27:15 +0100

C-x C-f /tmp/test-file
M-x enriched-mode RET
M-: (insert (propertize "foo" 'face '(:background "red"))) RET
C-x C-s

Error: Invalid face: :background

The backtrace is:
Debugger entered--Lisp error: (error "Invalid face" :background)
  internal-get-lisp-face-attribute(:background :foreground nil)
  face-attribute(:background :foreground)
  enriched-face-ans(:background)
  enriched-encode-other-face(nil :background)
  format-annotate-atomic-property-change(((bold-italic "bold" "italic") (bold "bold") (italic "italic") (underline "underline") (fixed "fixed") (excerpt "excerpt") (default) (nil enriched-encode-other-face)) nil :background)
  enriched-encode(1 4 #<buffer test-file-3>)
  format-encode-run-method(enriched-encode 1 4 #<buffer test-file-3>)
  format-annotate-function(text/enriched nil nil #<buffer test-file-3> 0)
  write-region(nil nil "/tmp/test-file-3" nil t "/private/tmp/test-file-3")
  basic-save-buffer-2()
  basic-save-buffer-1()
  basic-save-buffer(t)
  save-buffer(1)
  funcall-interactively(save-buffer 1)
  call-interactively(save-buffer nil nil)
  command-execute(save-buffer)

In GNU Emacs 27.0.50 (build 8, x86_64-apple-darwin10.8.0, NS appkit-1038.36 Version 10.6.8 (Build 10K549))
 of 2018-12-09 built on gray
Repository revision: d79bb75683ceb4eee2f753eb38fa8db99aff4568
Repository branch: master
Windowing system distributor 'Apple', version 10.3.1038
System Description:  Mac OS X 10.6.8