message: Check that the error should not be null
diff: @@ -152,7 +152,6 @@ suite(`${downloadAndInstallPackages.name}`, () => {
  new PackageInstallStart(),
  new DownloadStart(packageDescription),
  new DownloadFailure(`Failed to download from ${notDownloadablePackage[0].url}. Error code '404')`),
  - new InstallationFailure("downloadPackage", new PackageError("404", notDownloadablePackage[0]))
  ];
  await downloadAndInstallPackages(notDownloadablePackage, networkSettingsProvider, eventStream, downloadValidator);
  @@ -162,6 +161,7 @@ suite(`${downloadAndInstallPackages.name}`, () => {
  expect(obtainedEvents[2]).to.be.deep.equal(eventsSequence[2]);
  let installationFailureEvent = <InstallationFailure>obtainedEvents[3];
  expect(installationFailureEvent.stage).to.be.equal("downloadPackage");
  + expect(installationFailureEvent.error).to.not.be.null;
  });
  test("install.Lock is not present when the download fails", async () => {
  