Start to run steep in CI (line#515)

Using RBS, we were able to detect some minor bugs before release. It
also enabled detection of discrepancies between implementation and RBS.
We have now reduced errors in strict mode to zero!

To automatically catch issues in future changes, let's always verify
this. To achieve this, this change adds the job to run steep in CI.

Author: Yang-33

Rakefile

@@ -55,6 +55,11 @@ task :rbs do
   sh "bundle exec rbs -I sig validate"
 end
 
+desc "RBS type check (with steep)"
+task :rbs_steep do
+  sh "bundle exec steep check"
+end
+
 desc "RBS type check (with test)"
 task :rbs_test do
   Dir['lib/line/bot/v2/**/*.rb'].sort.each do |file|
@@ -110,6 +115,7 @@ task :ci do
   Rake::Task[:rubocop].invoke
   Rake::Task[:validate_yard_comment].invoke
   Rake::Task[:rbs].invoke
+  Rake::Task[:rbs_steep].invoke
   Rake::Task[:rbs_test].invoke
   Rake::Task[:build_test].invoke
 end

Steepfile

@@ -9,8 +9,7 @@ target :lib do
 
   library "net-http"
 
-  configure_code_diagnostics(D::Ruby.default)
-  # configure_code_diagnostics(D::Ruby.strict) # TODO: Enable strict checking
+  configure_code_diagnostics(D::Ruby.strict)
   # configure_code_diagnostics(D::Ruby.all_error) # TODO: Enable all error checking
 end
 

lib/line/bot/v2/utils.rb

@@ -57,7 +57,10 @@ def self.deep_camelize(object)
             object.map { |item| deep_camelize(item) }
           when Hash
             object.each_with_object({}) do |(k, v), new_object| # steep:ignore UnannotatedEmptyCollection
-              camel_key = camelize(k).to_sym
+              camel_key = camelize(k)
+              next if camel_key.nil?
+
+              camel_key = camel_key.to_sym
               new_value = v.is_a?(Array) || v.is_a?(Hash) ? deep_camelize(v) : v
               new_object[camel_key] = new_value
             end