Cannot subscribe to topics when using LDAP Plugin

-- PaulRinaldi - 24 Oct 2017

I get the following error whenever I try to subscribe to a topic using an LDAP user. I can subscribe without issue using a normal Foswiki user:

Error: ERROR: (500) Internal server error - Undefined subroutine &Foswiki::Contrib::MailerContrib::isSubscribedTo called at /var/www/foswiki/lib/Foswiki/Plugins/SubscribePlugin.pm line 149.
at /var/www/foswiki/lib/Foswiki/Plugins/SubscribePlugin.pm line 149.
Foswiki::Plugins::SubscribePlugin::_rest_subscribe('Foswiki=HASH(0x20c8ea8)', 'SubscribePlugin', 'subscribe', 'Foswiki::Response=HASH(0x20c8fe0)') called at /var/www/foswiki/lib/Foswiki/Func.pm line 768
Foswiki::Func::__ANON__('Foswiki=HASH(0x20c8ea8)', 'SubscribePlugin', 'subscribe', 'Foswiki::Response=HASH(0x20c8fe0)') called at /var/www/foswiki/lib/Foswiki/UI/Rest.pm line 280
Foswiki::UI::Rest::__ANON__() called at /usr/share/perl5/vendor_perl/Error.pm line 419
eval {...} called at /usr/share/perl5/vendor_perl/Error.pm line 411
Error::subs::try('CODE(0x327d4a0)', 'HASH(0x3286260)') called at /var/www/foswiki/lib/Foswiki/UI/Rest.pm line 295
Foswiki::UI::Rest::rest('Foswiki=HASH(0x20c8ea8)') called at /var/www/foswiki/lib/Foswiki/UI.pm line 374
Foswiki::UI::__ANON__() called at /usr/share/perl5/vendor_perl/Error.pm line 419
eval {...} called at /usr/share/perl5/vendor_perl/Error.pm line 411
Error::subs::try('CODE(0x11ce060)', 'HASH(0x20c8968)') called at /var/www/foswiki/lib/Foswiki/UI.pm line 500
Foswiki::UI::_execute('Foswiki::Request=HASH(0x209f198)', 'CODE(0x2124ff8)', 'rest', 1) called at /var/www/foswiki/lib/Foswiki/UI.pm line 326
Foswiki::UI::handleRequest('Foswiki::Request=HASH(0x209f198)') called at /var/www/foswiki/lib/Foswiki/Engine/CGI.pm line 100
Foswiki::Engine::CGI::run('Foswiki::Engine::CGI=HASH(0x19f1968)') called at /var/www/foswiki/bin/rest line 31.