[Fix #67] Fix an error for Performance/RedundantMerge

[koic]

Fixes #67.

This PR fixes an error for Performance/RedundantMerge when MaxKeyValuePairs option is set to null.

require: rubocop-performance

Performance/RedundantMerge:
  Enabled: true
  MaxKeyValuePairs: null

% bundle exec rubocop --only Performance/RedundantMerge -d
For /private/tmp/67: configuration from /private/tmp/67/.rubocop.yml
configuration from /Users/koic/.rbenv/versions/2.6.3/lib/ruby/gems/2.6.0/gems/rubocop-performance-1.4.0/config/default.yml
configuration from /Users/koic/.rbenv/versions/2.6.3/lib/ruby/gems/2.6.0/gems/rubocop-performance-1.4.0/config/default.yml
Default configuration from
/Users/koic/.rbenv/versions/2.6.3/lib/ruby/gems/2.6.0/gems/rubocop-0.72.0/config/default.yml
Inspecting 2 files
Scanning /private/tmp/67/Gemfile
.Scanning /private/tmp/67/example.rb
An error occurred while Performance/RedundantMerge cop was inspecting
/private/tmp/67/example.rb:23:2.
can't convert nil into Integer
/Users/koic/.rbenv/versions/2.6.3/lib/ruby/gems/2.6.0/gems/rubocop-performance-1.4.0/lib/rubocop/cop/performance/redundant_merge.rb:135:in
`Integer'
/Users/koic/.rbenv/versions/2.6.3/lib/ruby/gems/2.6.0/gems/rubocop-performance-1.4.0/lib/rubocop/cop/performance/redundant_merge.rb:135:in
`max_key_value_pairs'
/Users/koic/.rbenv/versions/2.6.3/lib/ruby/gems/2.6.0/gems/rubocop-performance-1.4.0/lib/rubocop/cop/performance/redundant_merge.rb:74:in
`non_redundant_pairs?'
/Users/koic/.rbenv/versions/2.6.3/lib/ruby/gems/2.6.0/gems/rubocop-performance-1.4.0/lib/rubocop/cop/performance/redundant_merge.rb:68:in `non_redundant_merge?

As with Width option of IndentationWidth cop, value of default.yml
is specified as the default value.

• https://github.com/rubocop-hq/rubocop-performance/blob/v1.4.0/lib/rubocop/cop/performance/redundant_merge.rb#L131
• https://github.com/rubocop-hq/rubocop/blob/v0.72.0/config/default.yml#L794-L801

---

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.

[ashmaroli]

@koic Shouldn't the || 2 be inside the parenthesis instead:

- Integer(cop_config['MaxKeyValuePairs']) || 2
+ Integer(cop_config['MaxKeyValuePairs'] || 2)

This way Integer() never operates on a nil value

[koic]

This is my mistake 💦 I opened a PR #74. Thanks!

[ashmaroli]

You're welcome @koic