Refactor pipeline errors_message

Use the shared method in Ci::Pipeline

app/models/ci/pipeline.rb

@@ -790,6 +790,10 @@ module Ci
       stages.find_by!(name: name)
     end
 
+    def error_messages
+      errors ? errors.full_messages.to_sentence : ""
+    end
+
     private
 
     def ci_yaml_from_repo

app/services/ci/create_pipeline_service.rb

@@ -65,7 +65,7 @@ module Ci
     def execute!(*args, &block)
       execute(*args, &block).tap do |pipeline|
         unless pipeline.persisted?
-          raise CreateError, pipeline.errors.full_messages.join(',')
+          raise CreateError, pipeline.error_messages
         end
       end
     end

spec/models/ci/pipeline_spec.rb

@@ -2998,4 +2998,28 @@ describe Ci::Pipeline, :mailer do
       end
     end
   end
+
+  describe '#error_messages' do
+    subject { pipeline.error_messages }
+
+    before do
+      pipeline.valid?
+    end
+
+    context 'when pipeline has errors' do
+      let(:pipeline) { build(:ci_pipeline, sha: nil, ref: nil) }
+
+      it 'returns the full error messages' do
+        is_expected.to eq("Sha can't be blank and Ref can't be blank")
+      end
+    end
+
+    context 'when pipeline does not have errors' do
+      let(:pipeline) { build(:ci_pipeline) }
+
+      it 'returns empty string' do
+        is_expected.to be_empty
+      end
+    end
+  end
 end