Fix insights notice text with YAML anchors

ee/changelogs/unreleased/fix-insights-note-bug.yml

+---
+title: Fix incorrect notice text on insights page
+merge_request: 31570
+author:
+type: fixed

ee/lib/gitlab/insights/project_insights_config.rb

@@ -7,7 +7,7 @@ module Gitlab
 
       def initialize(project:, insights_config:)
         @project = project
-        @insights_config = insights_config.deep_dup
+        @insights_config = insights_config_without_invalid_entries(insights_config.deep_dup)
       end
 
       def filtered_config
@@ -33,6 +33,11 @@ module Gitlab
       def includes_project?(project_ids_or_paths)
         project_ids_or_paths.any? { |item| item == project.id || item == project.full_path }
       end
+
+      # filtering out leftover YAML anchor keys
+      def insights_config_without_invalid_entries(config)
+        config.reject { |_, page_config| page_config[:title].nil? && page_config[:charts].nil? }
+      end
     end
   end
 end

ee/spec/lib/gitlab/insights/project_insights_config_spec.rb

@@ -30,6 +30,20 @@ describe Gitlab::Insights::ProjectInsightsConfig do
 
   subject { described_class.new(project: project, insights_config: config) }
 
+  context 'filtering out invalid config entries' do
+    let(:config_with_invalid_entry) { config.merge(".projectOnly": { projects: { only: [] } }) }
+
+    subject { described_class.new(project: project, insights_config: config_with_invalid_entry) }
+
+    it 'does not include invalid entry' do
+      expect(subject.filtered_config).to eq(config)
+    end
+
+    it 'does not show notice text' do
+      expect(subject.notice_text).to eq(nil)
+    end
+  end
+
   context 'when no projects.only filter present' do
     it 'does not change the config' do
       expect(subject.filtered_config).to eq(config)
@@ -51,7 +65,7 @@ describe Gitlab::Insights::ProjectInsightsConfig do
         expect(subject.filtered_config[:item1][:charts]).to eq([chart1])
       end
 
-      it 'has notice text' do
+      it 'does not have a notice text' do
         expect(subject.notice_text).not_to eq(nil)
       end
     end