fix: do not blow up when there are no matchers

lib/pact/matching_rules/v3/merge.rb

@@ -108,8 +108,10 @@ def handle_regex object, path, rules
         def log_ignored_rules
           @matching_rules.each do | jsonpath, rules_hash |
             rules_array = rules_hash["matchers"]
-            ((rules_array.length - 1)..0).each do | index |
-              rules_array.delete_at(index) if rules_array[index].empty?
+            if rules_array
+              ((rules_array.length - 1)..0).each do | index |
+                rules_array.delete_at(index) if rules_array[index].empty?
+              end
             end
           end
 

spec/lib/pact/matching_rules/v3/merge_spec.rb

@@ -513,5 +513,23 @@
         expect(subject).to eq Pact::SomethingLike.new("/some/path")
       end
     end
+
+    context "when there are no matchers" do
+      let(:expected) do
+        {
+          "name" => "Mary"
+        }
+      end
+
+      let(:matching_rules) do
+        {
+          "$.name" => {}
+        }
+      end
+
+      it "does not blow up" do
+        subject
+      end
+    end
   end
 end