Upgrade bosh-dns version from 1.35.1 to 1.36.0 breaks erb-render.rb

Upgrade bosh-dns version 1.35.1 to 1.36.0 breaks erb-render.rb with below error:

'ruby \
#    /home/jp/.bosh/installations/e76dc844-28f4-43e0-6616-014d00562498/tmp/erb-renderer582041556/erb-render.rb \
#    /home/jp/.bosh/installations/e76dc844-28f4-43e0-6616-014d00562498/tmp/erb-renderer582041556/erb-context.json \
#    /home/jp/.bosh/installations/e76dc844-28f4-43e0-6616-014d00562498/tmp/bosh-release-job3130417106/templates/config.json.erb \
#    /home/jp/.bosh/installations/e76dc844-28f4-43e0-6616-014d00562498/tmp/rendered-jobs428593803/config/config.json'

# stderr: '/home/jp/.bosh/installations/e76dc844-28f4-43e0-6616-014d00562498/tmp/erb-renderer582041556/erb-render.rb:189:in 
# `rescue in render': Error filling in template 
# '/home/jp/.bosh/installations/e76dc844-28f4-43e0-6616-014d00562498/tmp/bosh-release-job3130417106/templates/config.json.erb' 
# for bosh-dns/0 
# (line 44: #<NoMethodError: undefined method `downcase' for nil:NilClass>) (RuntimeError)

it seems the downcase method has changed.