NACK;
raw print:
array(3) { ["result"]=> string(4) "NACK" ["message"]=> string(36) "Halted; postid not set (getpostmeta)" ["stacktrace"]=> array(1) { ["tip"]=> string(53) "stacktrace suppressed; only available for admin users" } } pretty print:

• result => NACK
• message => Halted; postid not set (getpostmeta)
• stacktrace =>
  • tip => stacktrace suppressed; only available for admin users

(raw printed)