Ticket #47370 - DS crashes with some 7-bit check plugin configurations
    
    Bug description: DS crashed when some nsslapd-pluginarg were
    missing. The crash was resolved with the fix to #47340 but
    the correct error messages were not logged in some cases
    
    Fix description: This patch ensures that correct error messages
    are logged in the server error log
    
    https://fedorahosted.org/389/ticket/47370
    
    Reviewed by nhosoi.