Fix an error when ocurring cop error

[koic]

Follow #8908.

This PR fixes the following error when ocurring cop error.

% bundle exec rubocop
(snip)

1 file inspected, no offenses detected

1 error occurred:
An error occurred while Layout/ExtraSpacing cop was inspecting
/Users/koic/src/github.com/koic/rubocop-issues/43/example.rb.
undefined method `config_store' for nil:NilClass
/Users/koic/src/github.com/rubocop-hq/rubocop/lib/rubocop/version.rb:35:in
`extension_versions'
/Users/koic/src/github.com/rubocop-hq/rubocop/lib/rubocop/version.rb:21:in
`version'
/Users/koic/src/github.com/rubocop-hq/rubocop/lib/rubocop/cli/command/execute_runner.rb:62:in
`display_error_summary'
/Users/koic/src/github.com/rubocop-hq/rubocop/lib/rubocop/cli/command/execute_runner.rb:27:in
`execute_runner'
/Users/koic/src/github.com/rubocop-hq/rubocop/lib/rubocop/cli/command/execute_runner.rb:17:in
`run'

It suppresses unexpected undefined method config_store' for nil:NilClass`.

---

Before submitting the PR make sure the following are checked:

• Wrote good commit messages.
• Commit message starts with [Fix #issue-number] (if the related issue exists).
• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Added an entry to the Changelog if the new code introduces user-observable changes. See changelog entry format.
• The PR relates to only one subject with a clear title and description in grammatically correct, complete sentences.
• Run bundle exec rake default. It executes all tests and RuboCop for itself, and generates the documentation.

[koic]

@bbatsov I found an error due to #8908 that I would like to fix before RuboCop 1.0. This is the smallest patch and I would like to add a test later. 💦

[bbatsov]

Perfect timing! I'll likely the the release in an hour or two.

[koic]

Thank you! I’m so really excited!