Show an error when there is task-status list

[tcompa]

We observed this today, when submission failed before starting execution of tasks (due to external factors, namely SSH connection being down).
In this case, we cannot show any "failed" status next to a task, but we could show an error somewhere else in the page.

[tcompa]

The specific case that triggered this issue was fixed in fractal-server 2.3.11 (see fractal-analytics-platform/fractal-server#1728), but this remains valid for other cases where something fails before the first task started.

[zonia3000]

In #548 I've added a unit test for this case that is not easily reproducible in e2e tests.

I've manually tested it adding a raise Exception('foo') here: https://github.com/fractal-analytics-platform/fractal-server/blob/2e465134b65c2723e95c55bcfe7f7c4ade872f5c/fractal_server/app/runner/v2/__init__.py#L207

The result is the following: