Affected version grub2-2.06-80.el9 tested on ppc64le

• install RHEL-9.5 (I used RHEL-9.5.0-20240603.60)
• check grubenv content grub2-editenv list
  it should contain empty "next_entry=" line
• run grub2-reboot foobar (replace foobar with a non-existent boot entry title, if needed)
• check command exit code echo $?
• check grubenv content grub2-editenv list

Actual result:

• exit code 0
• grubenv contains next_entry=foobar line

Expected result:

• grub2 exits with non-zero exit code
• error message stating the requested boot entry does not exists is printed
• no changes to grubenv