Handle cookbook_version being Nil

[mbaitelman]

Version:

All versions of Chef CLI

Environment:

Tested in Docker

Scenario:

Run chef install (which resolves to chef-cli install) on a policyfile that has a cookbook dependency with missing information

Steps to Reproduce:

I can reproduce this each time on my repo though I do not know which of my cookbooks/dependencies are causing it

Expected Result:

Policyfile.lock should be generated

Actual Result:

Caching Cookbooks...
Error: Failed to generate Policyfile.lock
Reason: (NoMethodError) undefined method `metadata' for nil:NilClass

[afiune]

@mbaitelman thank you for filling this issue, also, thank you for your PR to add more logging info for troubleshooting. We are trying to reproduce this failure and we need more information from you to continue doing some troubleshooting:

1. Are you running on the latest version of Chef Workstation (chef -v)
2. Have you found the root cause of the issue? (From your PR it sounds like it is a Policyfile with a cookbook dependency that has no version on the metadata but we weren't able to replicate it that way)

After creating a Policyfile.rb with a cookbook dependency to bar cookbook that has no version on its metadata.rb, we have the following output of the chef install command:

➜  workspace chef install
Building policy example-application-service
Expanded run list: recipe[example_cookbook::default]
Caching Cookbooks...
Installing bar >= 0.0.0 from path
Using      example_cookbook 0.1.0

Lockfile written to /Users/afiune/chef/workspace/Policyfile.lock.json
Policy revision id: 5276887333b8f5c8d9a521888cda0538511f779b25c4ef30e7a41ebf4b3a5862