[FIX] web_editor: don't run code when input is emptied

Before this commit:
  - Edit mode, open image dialog
  - Upload an image to the media dialog
  - Reclick on Upload but don't select an image, close the browser image
    selector
  - This will trigger the input change event, as the input was emptied

This is needed since in later commit, `_addData()` will do some code outside
of the `files` loop, which is useless if there is no files selected.
In thise case, the issue would be that it would open an empty toastr.

task-2345082
Coming from #65828
Closes #68326

closes odoo/odoo#68334

X-original-commit: 94c45412714c1263788b2567ce3c9581453b2cd4
Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>

0 files changed, 0 insertions, 0 deletions