Add JavaScript sentry

app/controllers/submissions_controller.rb

@@ -190,9 +190,11 @@ class SubmissionsController < ApplicationController
               socket.send data
               Rails.logger.debug('Sent the received client data to docker:' + data)
             end
-          rescue JSON::ParserError
+          rescue JSON::ParserError => error
             socket.send data
             Rails.logger.debug('Rescued parsing error, sent the received client data to docker:' + data)
+            Raven.extra_context(data: data)
+            Raven.capture_exception(error)
           end
         end
 
@@ -395,7 +397,8 @@ class SubmissionsController < ApplicationController
     Rails.logger.debug('stopping submission ' + @submission.id.to_s)
     container = Docker::Container.get(params[:container_id])
     DockerClient.destroy_container(container)
-  rescue Docker::Error::NotFoundError
+  rescue Docker::Error::NotFoundError => error
+    Raven.capture_exception(error)
   ensure
     head :ok
   end
@@ -425,6 +428,7 @@ class SubmissionsController < ApplicationController
     yield(server_sent_event) if block_given?
     server_sent_event.write({code: 200}, event: 'close')
   rescue => exception
+    Raven.capture_exception(exception)
     logger.error(exception.message)
     logger.error(exception.backtrace.join("\n"))
     server_sent_event.write({code: 500}, event: 'close')