replace deprecated rack_response with error!

Author: markokajzer

lib/slack-ruby-bot-server/api/helpers/error_helpers.rb

@@ -10,14 +10,14 @@ module ErrorHelpers
             Middleware.logger.error "#{e.class.name}: #{e.message}\n  #{backtrace}"
             error = { type: 'other_error', message: e.message }
             error[:backtrace] = backtrace
-            rack_response(error.to_json, 400)
+            error!(error.to_json, 400)
           end
           # rescue document validation errors into detail json
           if SlackRubyBotServer::Config.mongoid?
             rescue_from Mongoid::Errors::Validations do |e|
               backtrace = e.backtrace[0..5].join("\n  ")
               Middleware.logger.warn "#{e.class.name}: #{e.message}\n  #{backtrace}"
-              rack_response({
+              error!({
                 type: 'param_error',
                 message: e.document.errors.full_messages.uniq.join(', ') + '.',
                 detail: e.document.errors.messages.each_with_object({}) do |(k, v), h|
@@ -29,7 +29,7 @@ module ErrorHelpers
           rescue_from Grape::Exceptions::Validation do |e|
             backtrace = e.backtrace[0..5].join("\n  ")
             Middleware.logger.warn "#{e.class.name}: #{e.message}\n  #{backtrace}"
-            rack_response({
+            error!({
               type: 'param_error',
               message: 'Invalid parameters.',
               detail: { e.params.join(', ') => [e.message] }
@@ -38,7 +38,7 @@ module ErrorHelpers
           rescue_from Grape::Exceptions::ValidationErrors do |e|
             backtrace = e.backtrace[0..5].join("\n  ")
             Middleware.logger.warn "#{e.class.name}: #{e.message}\n  #{backtrace}"
-            rack_response({
+            error!({
               type: 'param_error',
               message: 'Invalid parameters.',
               detail: e.errors.each_with_object({}) do |(k, v), h|