Fix access to constant `Gitlab::RepositorySizeError`

ee/app/services/ee/commits/create_service.rb

@@ -16,7 +16,7 @@ module EE
 
       def validate_repository_size!
         if project.above_size_limit?
-          raise_error(Gitlab::RepositorySizeError.new(project).commit_error)
+          raise_error(::Gitlab::RepositorySizeError.new(project).commit_error)
         end
       end
     end

ee/changelogs/unreleased/9800-500-error-when-trying-to-update-project-surpassing-repository-limit-through-the-web-interface.yml

+---
+title: Fix access to constant Gitlab::RepositorySizeError
+merge_request: 9579
+author:
+type: fixed

ee/spec/services/ee/commits/create_service_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Commits::CreateService do
+  let(:project) { create(:project) }
+  let(:user) { create(:user) }
+
+  before do
+    project.add_maintainer(user)
+  end
+
+  subject(:service) do
+    described_class.new(project, user, start_branch: 'master', branch_name: 'master')
+  end
+
+  describe '#execute' do
+    before do
+      stub_licensed_features(repository_size_limit: true)
+      project.update!(repository_size_limit: 1)
+      allow(project).to receive(:repository_and_lfs_size).and_return(2)
+    end
+
+    subject(:result) { service.execute }
+
+    it 'raises an error if the repositoy exceeds the size limit' do
+      expect(result[:status]).to be(:error)
+      expect(result[:message]).to eq('Your changes could not be committed, because this repository has exceeded its size limit of 1 Byte by 1 Byte')
+    end
+  end
+end