Tests in src/dynamic-import/catch don't fail if the error is not thrown

[nicolo-ribaudo]

Those templates are meant to test what error is thrown, but they pass if no error is thrown because they don't assert that the error happens. They only assert properties of the error if the error is indeed thrown.

I noticed this while writing import.defer tests, please don't fix it until when the import.defer PRs are merged :)