Channel generator fails if coffee-rails installed

[atstockland]

Steps to reproduce

Create a new rails 6 app. Run "bin/rails g channel message". The generator will complete successfully. Add coffee-rails gem, bundle, then re-run the channel generator command. The generator should fail with:

  "Could not find "javascript/channel.coffee" in any of your source paths."   ....

This may or may not be related to 24245

Expected behavior

A generated room_channel.coffee script file, or fallback room_channel.js file in app/javascript/channels

Actual behavior

The channel generator seems to be attempting to generate a coffee file, but fails.

System configuration

Rails version: Rails 6.0.0.rc1

Ruby version: ruby 2.6.2p47 (2019-03-13 revision 67232) [x86_64-darwin18]

[okuramasafumi]

How can we resolve this? I encounter this problem with rails 6.0.2.2 and coffee-rails 5.0.