Deployment Updater: Print error class name in case of unexpected error (#4647)

* without we have really little information what went wrong

Author: jochenehret

lib/cloud_controller/deployment_updater/updater.rb

@@ -59,7 +59,7 @@ def with_error_logging(error_message)
           if APPROVED_ERRORS.include?(e.class)
             deployment.update(error: e.message)
           else
-            deployment.update(error: 'An unexpected error has occurred.')
+            deployment.update(error: "An unexpected error has occurred: #{error_name}")
           end
         rescue StandardError => new_error
           logger.error(

spec/unit/lib/cloud_controller/deployment_updater/updater_spec.rb

@@ -184,7 +184,7 @@ module VCAP::CloudController
             subject.scale
           end.not_to raise_error
 
-          expect(deployment.error).to eq 'An unexpected error has occurred.'
+          expect(deployment.error).to eq 'An unexpected error has occurred: StandardError'
         end
       end
     end
@@ -396,7 +396,7 @@ module VCAP::CloudController
             subject.canary
           end.not_to raise_error
 
-          expect(deployment.error).to eq 'An unexpected error has occurred.'
+          expect(deployment.error).to eq 'An unexpected error has occurred: StandardError'
         end
       end
     end
@@ -429,7 +429,7 @@ module VCAP::CloudController
             subject.cancel
           end.not_to raise_error
 
-          expect(deployment.error).to eq 'An unexpected error has occurred.'
+          expect(deployment.error).to eq 'An unexpected error has occurred: StandardError'
         end
       end
     end
@@ -460,7 +460,7 @@ module VCAP::CloudController
 
           it 'provides a helpful error on the deployment model' do
             subject.scale
-            expect(deployment.error).to eq 'An unexpected error has occurred.'
+            expect(deployment.error).to eq 'An unexpected error has occurred: StandardError'
           end
         end