A previous commit (934e0896160272542dd00) modified QUnit to make sure we can display better tracebacks in debug=assets mode. However, this commit did not apply to errors coming from failing promises. To fix this, we can simply keep a reference to the error in that specific case. closes odoo/odoo#67048 Signed-off-by: Aaron Bohy (aab) <aab@odoo.com>