Fix rule.each on optional value

[bautrey37]

Skip processing rule.each on optional value when input is nil
When a key has a maybe macro, nil values are valid. However, if a
rule.each is specified on that key, an error is throw saying:

`block in each': undefined method `each_with_index' for nil:NilClass (NoMethodError)

[bautrey37]

I am now getting this rubocop warning after the change.

lib/dry/validation/rule.rb:79:7: C: Metrics/AbcSize: Assignment Branch Condition size for each is too high. [<8, 24, 6> 26/25]

I'm not sure what I can do to fix it.

[solnic]

Thanks for opening this PR. There was an issue with our CI setup in main, I just fixed it so could you rebase this branch and f-push? Also, don't worry about that rubocop warning.

[esparta]

Sometimes Rubocop is very picky and can be configure to have that ABC rule less problematic
Maybe is also time to reduce the amount of deepness in the method, from proc -> unless -> each_with_index to proc -> each_with_index

index bc05267..45ba724 100644
--- a/lib/dry/validation/rule.rb
+++ b/lib/dry/validation/rule.rb
@@ -82,16 +82,16 @@ module Dry
         @keys = []

         @block = proc do
-          unless result.base_error?(root) || !values.key?(root)
-            values[root].each_with_index do |_, idx|
-              path = [*Schema::Path[root].to_a, idx]
+          next if skip_values_evaluation?(root)

-              next if result.schema_error?(path)
+          values[root].each_with_index do |_, idx|
+            path = [*Schema::Path[root].to_a, idx]

-              evaluator = with(macros: macros, keys: [path], index: idx, &block)
+            next if result.schema_error?(path)

-              failures.concat(evaluator.failures)
-            end
+            evaluator = with(macros: macros, keys: [path], index: idx, &block)
+
+            failures.concat(evaluator.failures)
           end
         end

@@ -100,6 +100,15 @@ module Dry
         self
       end

+      # Helper to determine the need for value's review
+      #
+      # @api private
+      def skip_values_evaluation?(root)
+        result.base_error?(root) || !values.key?(root) || !values.key?(root)
+      end

[solnic]

@esparta thanks, we can address the metric separately from this PR though 😄

[bautrey37]

Thanks for merging this PR out! ❤️

I agree, the nesting is quite deep.