[29942] Better error messages for permission failures

[ci skip]

https://community.openproject.com/wp/29942

config/locales/en.yml

@@ -2659,6 +2659,7 @@ en:
       multipart_body_error: "The request body did not contain the expected multipart parts."
       multiple_errors: "Multiple field constraints have been violated."
       unable_to_create_attachment: "The attachment could not be created"
+      unable_to_create_attachment_permissions: "The attachment could not be saved due to lacking file system permissions"
       render:
         context_not_parsable: "The context provided is not a link to a resource."
         unsupported_context: "The resource given is not supported as context."

lib/api/errors/internal_error.rb

@@ -36,7 +36,7 @@ module API
       def initialize(error_message = nil)
         error = I18n.t('api_v3.errors.code_500')
 
-        if message
+        if error_message
           error += " #{error_message}"
         end
 

lib/api/v3/attachments/attachments_by_container_api.rb

@@ -93,7 +93,13 @@ module API
             raise ::API::Errors::ErrorBase.create_and_merge_errors(error.record.errors)
           rescue StandardError => error
             log_attachment_saving_error(error)
-            raise ::API::Errors::InternalError.new(I18n.t('api_v3.errors.unable_to_create_attachment'))
+            message =
+              if error&.class&.to_s == 'Errno::EACCES'
+                I18n.t('api_v3.errors.unable_to_create_attachment_permissions')
+              else
+                I18n.t('api_v3.errors.unable_to_create_attachment')
+              end
+            raise ::API::Errors::InternalError.new(message)
           end
 
           def log_attachment_saving_error(error)