tab selected should be adjacent when closing last one.

fixes #13886

contributed on behalf of STMicroelectronics

Signed-off-by: Remi Schnekenburger <rschnekenburger@eclipsesource.com>

packages/core/src/browser/shell/application-shell.ts

@@ -1896,6 +1896,10 @@ export class ApplicationShell extends Widget {
  if (index < current.titles.length - 1) {
  return index + 1;
  }
+ // last item in tab bar. select the previous one.
+ if (index === current.titles.length - 1) {
+ return index - 1;
+ }
  return 0;
  }