Fix feature flag error

The `feature_flag:` key doesn't seem to work with our new YAML feature
flag flow. Therefore, we'll stop using it and make the field `nil` if
the feature flag is disabled

doc/api/graphql/reference/index.md

@@ -4651,7 +4651,7 @@ An edge in a connection.
 | `alertManagementIntegrations` | [`AlertManagementIntegrationConnection`](#alertmanagementintegrationconnection) | Integrations which can receive alerts for the project. |
 | `alertManagementPayloadFields` | [`[AlertManagementPayloadAlertField!]`](#alertmanagementpayloadalertfield) | Extract alert fields from payload for custom mapping. |
 | `allowMergeOnSkippedPipeline` | [`Boolean`](#boolean) | If `only_allow_merge_if_pipeline_succeeds` is true, indicates if merge requests of the project can also be merged with skipped jobs. |
-| `apiFuzzingCiConfiguration` | [`ApiFuzzingCiConfiguration`](#apifuzzingciconfiguration) | API fuzzing configuration for the project. Available only when feature flag `api_fuzzing_configuration_ui` is enabled. |
+| `apiFuzzingCiConfiguration` | [`ApiFuzzingCiConfiguration`](#apifuzzingciconfiguration) | API fuzzing configuration for the project. Null unless feature flag `api_fuzzing_configuration_ui` is enabled. |
 | `archived` | [`Boolean`](#boolean) | Indicates the archived status of the project. |
 | `autocloseReferencedIssues` | [`Boolean`](#boolean) | Indicates if issues referenced by merge requests and commits within the default branch are closed automatically. |
 | `avatarUrl` | [`String`](#string) | URL to avatar image file of the project. |

ee/app/graphql/ee/types/project_type.rb

@@ -129,8 +129,8 @@ module EE
         field :api_fuzzing_ci_configuration,
               ::Types::AppSec::Fuzzing::Api::CiConfigurationType,
               null: true,
-              description: 'API fuzzing configuration for the project.',
-              feature_flag: :api_fuzzing_configuration_ui
+              description: 'API fuzzing configuration for the project. '\
+                           'Null unless feature flag `api_fuzzing_configuration_ui` is enabled.'
 
         field :push_rules,
               ::Types::PushRulesType,
@@ -140,7 +140,8 @@ module EE
       end
 
       def api_fuzzing_ci_configuration
-        return unless Ability.allowed?(current_user, :read_vulnerability, object)
+        return unless ::Feature.enabled?(:api_fuzzing_configuration_ui, object, default_enabled: :yaml) && \
+                      Ability.allowed?(current_user, :read_vulnerability, object)
 
         configuration = ::AppSec::Fuzzing::Api::CiConfiguration.new(project: object)
 

ee/spec/requests/api/graphql/app_sec/fuzzing/api/ci_configuration_type_spec.rb

@@ -74,7 +74,7 @@ RSpec.describe 'Query.project(fullPath).apiFuzzingCiConfiguration' do
         stub_licensed_features(security_dashboard: false)
       end
 
-      it 'returns null' do
+      it 'returns nil' do
         post_graphql(query, current_user: user)
 
         expect(response).to have_gitlab_http_status(:ok)
@@ -90,13 +90,12 @@ RSpec.describe 'Query.project(fullPath).apiFuzzingCiConfiguration' do
       stub_feature_flags(api_fuzzing_configuration_ui: false)
     end
 
-    it 'errors' do
+    it 'returns nil' do
       post_graphql(query, current_user: user)
 
       expect(response).to have_gitlab_http_status(:ok)
-      expect(graphql_errors.first['message']).to eq(
-        "Field 'apiFuzzingCiConfiguration' doesn't exist on type 'Project'"
-      )
+      fuzzing_config = graphql_data.dig('project', 'apiFuzzingCiConfiguration')
+      expect(fuzzing_config).to be_nil
     end
   end
 end