Mysql query failed but I'm not getting specific error - php

Question

Something really weird is going on here. I have this method for mysqli query.
public function select($options) {
$default = array (
'table' => '',
'fields' => '*',
'condition' => '2',
'order' => '1',
'limit' => 50
);
$options = array_merge($default,$options);
$query = "SELECT {$options['fields']} FROM {$options['table']} WHERE {$options['condition']} ORDER BY {$options['order']} LIMIT {$options['limit']}";
if ($result = $this->conn->query($query)) {
while ($row = $result->fetch_assoc()) {
$rows[] = $row;
}
return $rows;
} else {
printf("Query failed: %s\n", $mysqli->error);
exit;
}
}
Once the query get executed I get $rows and everything works like a charm. But then when I try to get specific key in array I get the "Query failed:" without specific message :S
$options = array(
'table' => 'settings',
'fields' => 'setting_wall_post,setting_status_tag,setting_photo,setting_like,setting_comment',
'limit' => '1',
'condition' => "setting_id = 6",
);
$check = $this->mysql->select($options);
print_r($check);
$check = $check[0];
if($check["setting_wall_post"]) //if I comment out this IF block it works :(
$this->scope["wall_post"] = "publish_stream";
Also I've tried to close mysqli connection and then I get
Warning: mysqli::query() [mysqli.query]: Couldn't fetch mysqli
this IF block is acting like it works with mysqli :S
So the question is, what is the issue here? Why can't I access to "setting_wall_post"? I guess that part is the problem since it works if I comment out that IF block.

Answer 1

Edit. What a silly I am, overlooked such a typo: $this->conn have to be used instead of undefined $mysqli.
That's why one should always have error reporting no less than E_ALL
The code you posted just cannot cause this kind of error.
Change your error reporting code to this one
} else {
throw new Exception($this->conn->error);
}
this way you will have a stack trace which will show the chain of calls, pointing to the place of code that caused particular error.
BTW, the whole function looks unusable and error prone to me. it is open to injection and require more code than a conventional SQL