Improve error messages regarding initial-buffer-choice (Bug#29098)

* lisp/startup.el (command-line-1) <initial-buffer-choice>: Make the
messages conform to Emacs conventions, and show the invalid return
value in the message.

1 files changed, 2 insertions, 2 deletions

diff --git a/lisp/startup.el b/lisp/startup.el
index 33f8ca63f8d..63b831ee38d 100644
--- a/lisp/startup.el
+++ b/lisp/startup.el
@@ -2515,9 +2515,9 @@ nil default-directory" name)
                    ((eq initial-buffer-choice t)
                     (get-buffer-create "*scratch*"))
                    (t
-                    (error "initial-buffer-choice must be a string, a function, or t.")))))
+                    (error "`initial-buffer-choice' must be a string, a function, or t")))))
         (unless (buffer-live-p buf)
-          (error "initial-buffer-choice is not a live buffer."))
+          (error "Value returned by `initial-buffer-choice' is not a live buffer: %S" buf))
         (setq displayable-buffers (cons buf displayable-buffers))))
 
     ;; Display the first two buffers in `displayable-buffers'.  If