php - Msqli Statement error not returning anything -

straight mysqli book:

<?php /* prepared statement, stage 2: bind , execute */ $id = 1; if (!$stmt->bind_param("i", $id)) {     echo "binding parameters failed: (" . $stmt->errno . ") " . $stmt->error; }  if (!$stmt->execute()) {     echo "execute failed: (" . $stmt->errno . ") " . $stmt->error; } ?> 

the problem $stmt->error doesnt return on false!

echo $stmt->error; returns nothing blank!!

i checking $stmt->error if bind_param false bind_param not set $stmt->error on false. php manual claims not! bind_param return warning if not executed correctly or number of parameter types not match number of parameters.