OutputEvent objects should respect output severity

[roblourens]

If category is stderr, then 'variables' is never called.

[isidorn]

@roblourens looking at the code we do not use severity in a case for OutputEvent with a variablesReference. It is simply ignored.

For me to investigate further I would need exact repro steps

[roblourens]

Sorry, I must have changed two things at once, because the actual problem I'm having is with this check event.body.output.length > 0. I think output shouldn't be required in this case, since it's ignored.

[roblourens]

But the fact that severity is ignored is also an issue, right? Opened a new issue for the output part - #16527

[roblourens]

I was hoping to use variablesReference for all output events, not just ones that contain objects, for consistency. If it's better to check the types that were logged and fall back on the original behavior for strings, I can do that. But I think it would be good if there could be an indicator that an object was logged as an error, or thrown. It should stand out if you're skimming the log.

[isidorn]

@roblourens but what would happen if you log an object as an error. Only the top level object would get decorated as an error or all children would also get decorated as an error.
I am not seeing a huge value in adding this. Putting it to the backlog until there is a clear use case for this.