Undefined method `keys'

Hi,

I'm getting the following error when trying to use your relay script with sensu server. Is tehre anything I could be missing/incorrectly configured?

{"timestamp":"2017-07-25T14:18:49.023065+0100","level":"info","message":"configuring sensu spawn","settings":{"limit":12}} {"timestamp":"2017-07-25T14:18:49.303677+0100","level":"error","message":"redis connection error","error":"unable to connect to redis server"} /etc/sensu/extensions/handlers/relay.rb:185:in post_init': undefined method keys' for nil:NilClass (NoMethodError) from /opt/sensu/embedded/lib/ruby/gems/2.4.0/gems/sensu-extension-1.5.1/lib/sensu/extension.rb:19:in block in initialize'
from /opt/sensu/embedded/lib/ruby/gems/2.4.0/gems/eventmachine-1.2.2/lib/eventmachine.rb:977:in block in run_deferred_callbacks' from /opt/sensu/embedded/lib/ruby/gems/2.4.0/gems/eventmachine-1.2.2/lib/eventmachine.rb:974:in times'
from /opt/sensu/embedded/lib/ruby/gems/2.4.0/gems/eventmachine-1.2.2/lib/eventmachine.rb:974:in run_deferred_callbacks' from /opt/sensu/embedded/lib/ruby/gems/2.4.0/gems/eventmachine-1.2.2/lib/eventmachine.rb:194:in run_machine'
from /opt/sensu/embedded/lib/ruby/gems/2.4.0/gems/eventmachine-1.2.2/lib/eventmachine.rb:194:in run' from /opt/sensu/embedded/lib/ruby/gems/2.4.0/gems/sensu-1.0.0/lib/sensu/server/process.rb:33:in run'
from /opt/sensu/embedded/lib/ruby/gems/2.4.0/gems/sensu-1.0.0/exe/sensu-server:10:in <top (required)>' from /opt/sensu/bin/sensu-server:22:in load'
from /opt/sensu/bin/sensu-server:22:in <main>'