don't include empty arrays, particularly on scope[:joins] because scope[:joins].to_s returns strings like #<ActiveRecord::Relation:0x5021304> breaking the subsequent 'joins.join(" ")'
don't include empty arrays, particularly on scope[:joins] because scope[:joins].to_s returns strings like #<ActiveRecord::Relation:0x5021304> breaking the subsequent 'joins.join(" ")'

Signed-off-by: Joel Nimety <3f71976debff298f9dcfc4f088718d2f0a9263e7@continuity.net>

seven1m/acts_as_taggable_on_steroids,jviney/acts_as_taggable_on_steroids