Precompile with defer, invalid Dockerfile

[SaihttamR]

Adding the parameter ‘--precompile=defer’ an invalid Dockerfile is created.

$ rails generate dockerfile --precompile=defer
...
Dockerfile:27
--------------------
  25 |     
  26 |     
  27 | >>> FROM prebuild as node
  28 |     
  29 |     # Install JavaScript dependencies
--------------------
ERROR: failed to solve: prebuild: pull access denied, repository does not exist or may require authorization: server message: insufficient_scope: authorization failed

I changed line 5 and append "as prebuild" to fix it.

FROM ruby:$RUBY_VERSION-slim as prebuild