Audit plugin crashes when the author dn is not found in the LDAP

Description

Dans le plug-in audit, quand je clique sur une ligne du type "fake-dn",

j'obtiens l'erreur PHP suivante

Fatal error: Uncaught exception 'NonExistingLdapNodeException' with message 'Dn fake_dn not found in LDAP' in /usr/share/fusiondirectory/include/class_objects.inc:282 
Stack trace: 
#0 /usr/share/fusiondirectory/plugins/admin/audit/class_auditEvent.inc(40): objects::link('fake_dn', 'user') 
#1 /usr/share/fusiondirectory/include/simpleplugin/class_Attribute.inc(573): UserLinkAttribute->renderFormInput() 
#2 /usr/share/fusiondirectory/include/simpleplugin/class_simplePlugin.inc(848): Attribute->renderAttribute(Array, false) #3 /usr/share/fusiondirectory/include/simpleplugin/class_simplePlugin.inc(705): simplePlugin->renderAttributes(false) 
#4 /usr/share/fusiondirectory/include/simpleplugin/class_simpleTabs.inc(198): simplePlugin->execute() 
#5 /usr/share/fusiondirectory/include/simpleplugin/class_simpleManagement.inc(574): simpleTabs->execute() 
#6 /usr/share/fusiondirectory/include/simpleplugin/class_simpleManagement.inc(1337): simpleManagement->execute() 
#7 /usr/share/fusiondirectory/plugins/admin/audit/main.inc(21): simpleMana in /usr/share/fusiondirectory/include/class_objects.inc on line 282

Distribution Name and Version

Debian 8.10 Jessie

FusionDirectory Version

1.2-2~jenkinsbuild99

Plugin with the defect

Audit

PHP version used

PHP 5.6.33-0+deb8u1 (cli) (built: Jan 5 2018 15:46:26)

Origin of php packages

Debian 8.10 jessie

Steps to Reproduce

1. [First Step]
2. [Second Step]
3. [and so on...]

Expected behavior:

le plugin audit ne devrait pas crashe

Actual behavior:

le plugin provoque une erreur

Reproduces how often:

100%

Additional Information