USER ERROR Message: SQLSTATE[23000] - SQL Message Error when accepting an alliance member

Expected behavior

I was expecting a successful message indicating that a new alliance member of the alliance has been accepted.

Actual behavior

When I was just about to accept a new member for the alliance, I received an SQL error instead of a successful message. Every time I see this url

• https://steemnova.intinte.org/game.php?page=alliance&mode=admin&action=sendAnswerToApply&id=152

the same message appears. The message contains information that may be important and should not be visible to everyone.

How to reproduce

I assume that this error is displayed if you want to accept a member who has already been accepted.

• Browser: Chrome Version 64.0.3282.140 (Offizieller Build) (64-Bit)

• Operating system: Mac OSX

Recording Of The Bug

    USER ERROR
Message: SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'message_owner' cannot be null

Query-Code:INSERT INTO uni1_messages SET message_owner  = , message_sender  = 134, message_time = 1519078537, message_type  = 2, message_from   = AllianzD-A-CH [GER], message_subject = Sie wurden aufgenommen bei D-A-CH, message_text    = Hallo!
Die Allianz D-A-CH hat Ihre Bewerbung akzeptiert.
Begründung: 
, message_unread    = 1, message_universe = 1;
File: /includes/classes/Database.class.php
Line: 126
URL: https://steemnova.intinte.org/game.php?page=alliance&mode=admin&action=sendAnswerToApply&id=152
PHP-Version: 7.0.27-1
PHP-API: fpm-fcgi
2Moons Version: 1.8.git
Debug Backtrace:
#0 /includes/classes/Database.class.php(185): Database->_query('INSERT INTO uni...', Array, 'insert')
#1 /includes/classes/PlayerUtil.class.php(644): Database->insert('INSERT INTO %%M...', Array)
#2 /includes/pages/game/ShowAlliancePage.class.php(1179): PlayerUtil::sendMessage(NULL, '134', 'AllianzD-A-CH [...', 2, 'Sie wurden aufg...', 'Hallo!<br>Die A...', 1519078537)
#3 /includes/pages/game/ShowAlliancePage.class.php(735): ShowAlliancePage->adminSendAnswerToApply()
#4 /game.php(57): ShowAlliancePage->admin()
#5 {main}