Pack does not print errors to STDERR

[zmackie]

During failed creation of a builder, I noticed errors don't propogate to STDERR

/tmp/build/59a8880f/pack-cli/pack create-builder localhost:5000/cloundry/cnb:bionic --builder-config /tmp/build/59a8880f/builder.toml --publish -v 2>err
Creating builder localhost:5000/cloudfoundry/cnb:bionic from build-image cloudfoundry/build:base-cnb
Using cached version of https://github.com/buildpacks/lifecycle/releases/download/v0.5.0/lifecycle-v0.5.0+linux.x86-64.tgz
ERROR: validating buildpacks: buildpack org.cloudfoundry.node-engine@0.0.124 not found on the builder

#cat err
[ITS EMPTY]

root@45fa57ec-7290-4959-619c-6c1af8ba6ada:/tmp/build/59a8880f# /tmp/build/59a8880f/pack-cli/pack report
Pack:
  Version:  v0.6.0 (git sha: 109b629d388cec0ed3836b9fed6717727a9187c1)
  OS/Arch:  linux/amd64

Default Lifecycle Version:  0.5.0

Config:
(error: open /root/.pack/config.toml: no such file or directory)