array_column() expects parameter 1 to be array, null given

I have a teamspeak3 bot written in PHP and when i ty to start the bot i get this error: PHP Warning: array_column() expects parameter 1 to be array, null given... on line 13,and the line 13 is the $clientonchannel, i don't know hot to make'it work, some help is appreciated. Im new with this.

PHP Code:
    $config['function']['pokeonchannel'] = Array(
        'enable' => true,
        'info' => Array(
            1 => Array(
                'channel' => 20,
                'pokegroup' => Array(103,110),
                'message' => "[NICK] message to user",
            )
        ),
        'interval' => Array('days' => 0, 'hours' => 0, 'minutes' => 0, 'seconds' => 30), //interval
        'datazero' => '1970-01-01 00:00:00'
    );

 foreach($config['function']['pokeonchannel']['info'] as $pokeid)
   {
      $admincount = 0;
      $admincount2 = 0;
      $clientonchannel = array_keys(array_column($user['data'], 'cid'), $pokeid['channel']); **// This is line 13**

 if(isset($clientonchannel[0]))
  { 
    foreach($pokeid['pokegroup'] as $pokegroup)
     {
        $groupclients = $tsAdmin -> serverGroupClientList($pokegroup, $names = true);
             foreach($groupclients['data'] as $clientid)
                 {
                     $client = $tsAdmin -> clientFind($clientid['client_nickname']);
                       if($client['data'])
                                {
                                    $admin = $tsAdmin-> clientInfo($client['data'][0]['clid']);
                                    if(!in_array($admin['data']['cid'], $config['function']['helpchannel']['ignoredonchannel']))
                                    {
                                        $pokemessage = str_replace('[NICK]', $user['data'][$clientonchannel[0]]['client_nickname'], $pokeid['message']);
                                        $tsAdmin -> clientPoke($client['data'][0]['clid'], $pokemessage);
                                        $admincount++;
}
                                    else
                                    {
                                        $admincount2++;
                                    }
                                }
                            }
                        }
                        if($admincount == 0 && $admincount2==1)
                                    {$tsAdmin -> clientPoke($user['data'][$clientonchannel[0]]['clid'], "\n[b]".$language['pokeonchannel']['busy']."[/b]");
                                        return;
                                    }
                                    else if($admincount == 0 && $admincount2>1)
                                    {
                                        $tsAdmin -> clientPoke($user['data'][$clientonchannel[0]]['clid'], "\n[b]".$language['pokeonchannel']['busy2']."[/b]"); 
                                        return;
                                    }
                                    else if($admincount == 0)
                                    {
                                        $tsAdmin -> clientPoke($user['data'][$clientonchannel[0]]['clid'], "\n[b]".$language['pokeonchannel']['lackadministration']."[/b]");    
                                        return;
                                    }
                                    else if($admincount == 1)
                                    {
                                        $tsAdmin -> clientPoke($user['data'][$clientonchannel[0]]['clid'], "\n[b]".$language['pokeonchannel']['aware']."[/b]");
                                        return;
                                    }
                                    else
                                    {
                                        $tsAdmin -> clientPoke($user['data'][$clientonchannel[0]]['clid'], "\n[b]".$language['pokeonchannel']['aware2']."[/b]");
                                        return;
                                    }

                    }
                }

I think variable $user does not exist. you can make a variable called $user and fetch details in it.

$sql = "SELECT data FROM users where id = {user id}";
$user = $conn->query($sql);