Simplify error message handling in Projects::CreateService

There's no need to add a redundant message to the errors if the
model is invalid. This cleans up the message as well for the importer.

app/controllers/import/base_controller.rb

@@ -27,11 +27,6 @@ class Import::BaseController < ApplicationController
   end
 
   def project_save_error(project)
-    # Projects::CreateService will set base message if unable to save
-    if project.errors[:base].present?
-      project.errors[:base].last
-    else
-      project.errors.full_messages.join(', ')
-    end
+    project.errors.full_messages.join(', ')
   end
 end

app/services/projects/create_service.rb

@@ -63,6 +63,7 @@ module Projects
       message = "Unable to save #{e.record.type}: #{e.record.errors.full_messages.join(", ")} "
       fail(error: message)
     rescue => e
+      @project.errors.add(:base, e.message) if @project
       fail(error: e.message)
     end
 
@@ -141,7 +142,6 @@ module Projects
       Rails.logger.error(log_message)
 
       if @project
-        @project.errors.add(:base, message)
         @project.mark_import_as_failed(message) if @project.persisted? && @project.import?
       end
 

spec/support/controllers/githubish_import_controller_shared_examples.rb

@@ -119,21 +119,6 @@ shared_examples 'a GitHub-ish import controller: POST create' do
   end
 
   it 'returns 422 response with the base error when the project could not be imported' do
-    project = build(:project)
-    error_message = 'This is an error'
-    project.errors.add(:base, error_message)
-
-    allow(Gitlab::LegacyGithubImport::ProjectCreator)
-      .to receive(:new).with(provider_repo, provider_repo.name, user.namespace, user, access_params, type: provider)
-        .and_return(double(execute: project))
-
-    post :create, format: :json
-
-    expect(response).to have_gitlab_http_status(422)
-    expect(json_response['errors']).to eq(error_message)
-  end
-
-  it 'returns 422 response with a combined error when the project could not be imported' do
     project = build(:project)
     project.errors.add(:name, 'is invalid')
     project.errors.add(:path, 'is old')