fix: error message in the checkout after basket has expired

[SGrueber]

PR Type

[x] Bugfix [ ] Feature [ ] Code style update (formatting, local variables) [ ] Refactoring (no functional changes, no API changes) [ ] Build-related changes [ ] CI-related changes [ ] Documentation content changes [ ] Application / infrastructure changes [ ] Other:

What Is the Current Behavior?

If an error occurs because the basket has expired an error message 'undefined' is shown on checkout pages.
Find a more detailed bug description in the issue below.

Issue Number: Closes #1669

What Is the New Behavior?

The message 'The cart could not be found' is shown instead. If the user tries to continue checkout he is navigated to the (empty) cart page.

Does this PR Introduce a Breaking Change?

[ ] Yes [x] No

Other Information

AB#97978