DEV: Allow enum typed theme objects property to be optional (#26571)

This commit changes enum typed theme objects property to be optional.
Previously, an enum typed property is always required but we have found
that this might not be ideal so we want to change it.

spec/lib/theme_settings_object_validator_spec.rb

@@ -155,8 +155,8 @@ RSpec.describe ThemeSettingsObjectValidator do
     end
 
     context "for enum properties" do
-      let(:schema) do
-        {
+      def schema(required: false)
+        property = {
           name: "section",
           properties: {
             enum_property: {
@@ -165,6 +165,9 @@ RSpec.describe ThemeSettingsObjectValidator do
             },
           },
         }
+
+        property[:properties][:enum_property][:required] = true if required
+        property
       end
 
       it "should not return any error messages when the value of the property is in the enum" do
@@ -184,14 +187,16 @@ RSpec.describe ThemeSettingsObjectValidator do
         )
       end
 
-      it "should return the right hash of error messages when enum property is not present" do
-        errors = described_class.new(schema: schema, object: {}).validate
+      it "should not return any error messages when enum property is not present but is not required" do
+        expect(described_class.new(schema: schema(required: false), object: {}).validate).to eq({})
+      end
+
+      it "should return the right hash of error messages when enum property is not present and is required" do
+        errors = described_class.new(schema: schema(required: true), object: {}).validate
 
         expect(errors.keys).to eq(["/enum_property"])
 
-        expect(errors["/enum_property"].full_messages).to contain_exactly(
-          "must be one of the following: [\"choice 1\", 2, false]",
-        )
+        expect(errors["/enum_property"].full_messages).to contain_exactly("must be present")
       end
     end