Notifications silently die when the notification command is bad/unreachable/absent

[DonKiShoot]

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BUG REPORT INFORMATION

Centreon Web version: 18.10

Centreon Engine version: 18.10

Centreon Broker version: 18.10

OS: Centos 7.5

Additional environment details (AWS, VirtualBox, physical, etc.) : Physical

Steps to reproduce the issue:

1. Just put a bad command in notification

Describe the results you received:
No mail received

Describe the results you expected:
An alert somewhere on the GUI or in the centengine log (prefixed with "Error:") describe that a command failed with the "command" and the "output error".
Maybe create a developer mode in the GUI which will help us not loosing time in debugging as a lot of thing could failed (rights on folders, data not well formated, binary absent, etc ...).

Additional information you think important (e.g. issue happens only occasionally):
Sample of the centengine log which do not indicate an error :-( :
Raw notification command: /usr/bin/php -q $USER1$/nagios_mail.php
[1541505441] [13903] Processed notification command: /usr/bin/php -q /usr/lib64/nagios/plugins/nagios_mail.php

Luckily i tried the command line and saw that /usr/bin/php doesn't exist.

Thanks for the next versions :-)