Rescue and log errors raised when preparing builds

https://gitlab.com/gitlab-org/gitlab-ce/issues/60480

app/services/ci/prepare_build_service.rb

@@ -11,9 +11,11 @@ module Ci
     def execute
       prerequisites.each(&:complete!)
 
-      unless build.enqueue
-        build.drop!(:unmet_prerequisites)
-      end
+      build.enqueue!
+    rescue => e
+      Gitlab::Sentry.track_acceptable_exception(e, extra: { build_id: build.id })
+
+      build.drop(:unmet_prerequisites)
     end
 
     private

spec/services/ci/prepare_build_service_spec.rb

@@ -38,7 +38,21 @@ describe Ci::PrepareBuildService do
         end
 
         it 'drops the build' do
-          expect(build).to receive(:drop!).with(:unmet_prerequisites).once
+          expect(build).to receive(:drop).with(:unmet_prerequisites).once
+
+          subject
+        end
+      end
+
+      context 'prerequisites raise an error' do
+        before do
+          allow(prerequisite).to receive(:complete!).and_raise Kubeclient::HttpError.new(401, 'unauthorized', nil)
+        end
+
+        it 'drops the build and notifies Sentry' do
+          expect(build).to receive(:drop).with(:unmet_prerequisites).once
+          expect(Gitlab::Sentry).to receive(:track_acceptable_exception)
+            .with(instance_of(Kubeclient::HttpError), hash_including(extra: { build_id: build.id }))
 
           subject
         end