application.yml.erb does not work

[aleita]

once I've manually and successfully executed the template templates/etc/storm/webdav/config/application.yml.erb
I got the following error

Error: Could not retrieve catalog from remote server: Error 500 on SERVER: Server Error: Evaluation Error: Error while evaluating a Function Call, Failed to parse template storm/application.yml.erb:
  Filepath: /etc/puppetlabs/code/environments/prebatch/modules/storm/templates/application.yml.erb
  Line: 4
  Detail: undefined method `each' for nil:NilClass
 (file: /etc/puppetlabs/code/environments/prebatch/manifests/storage/webdav-dc.pp, line: 18, column: 17) on node webdav-dc.recas.ba.infn.it
Warning: Not using cache on failed catalog
Error: Could not retrieve catalog; skipping run

I fixed this issue just adding a variable declaration in class storm::webdav like this

Array $oauth_issuers,

Ale