[Error Handling] Backend - Test section improvements

[xoscar]

This ticket is part of the epic #2040 to improve the UX/UI when running a test

AC1
As a client that just executed a test run
And fetching the trace was successful
But generating some of the outputs that failed
The backend should handle the error
And trigger output events for each of the affected entries

AC2
As a client that just executed a test run
And fetching the trace was successful
But executing/parsing/evaluating some of the test specs that failed
The backend should handle the error
And trigger test specs error events for each of the affected entries

[xoscar]

This might be done, double check and possibly close this one to just focus on the FE part