message: empty string is a valid response for plugins
diff: @@ -24,7 +24,7 @@ export function sendMessage(id, payload) {
  return browser.runtime
  .sendMessage(id, payload)
  .then(response => {
  - if (!response) {
  + if (response === undefined || response === null) {
  return Promise.reject(
  new NoResponseError(
  `${Manager.getPlugin(id).name} plugin did not respond`
  