Fix invocation with --debug-init and changes to debug-ignored-errors

* src/eval.c (syms_of_eval) <debug-ignored-errors>: Mention in the
doc string the caveat with removing errors from the standard value
while invoking Emacs with --debug-init.

* lisp/startup.el (startup--load-user-init-file): If the user's
init files add to the value of 'debug-ignored-errors', make sure
the additions are preserved after restoring the value we reset
during loading the init file, if Emacs was invoked with
"--debug-init".  (Bug#65267)

1 files changed, 4 insertions, 0 deletions

diff --git a/src/eval.c b/src/eval.c
index 9e54d489a3b..9268b65aa85 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -4296,6 +4296,10 @@ See also the variable `debug-on-quit' and `inhibit-debugger'.  */);
 Each element may be a condition-name or a regexp that matches error messages.
 If any element applies to a given error, that error skips the debugger
 and just returns to top level.
+If you invoke Emacs with --debug-init, and want to remove some
+elements from the default value of this variable, use `setq' to
+change the value of the variable to a new list, rather than `delq'
+to remove some errors from the list.
 This overrides the variable `debug-on-error'.
 It does not apply to errors handled by `condition-case'.  */);
   Vdebug_ignored_errors = Qnil;