[Alerting] Missing CTA in error mode in Index Theshold

[gmmorris]

When Index Threshold goes into an error state it no longer shows the user which field is missing (the Index field).

It should still say "Select a field" or something to that effect, I think.

[elasticmachine]

Pinging @elastic/kibana-alerting-services (Team:Alerting Services)

[gmmorris]

After discussing with @mdefazio seems this is in line with how the Expression components behave in other places in Kibana- so he'll discuss with the team to see if this is correct.

One thing I still think we might want to address is that we message "Expression contains errors" but it's very unclear now what is actually invalid.
My thinking is that we should either make the message clear that the Index field is invalid, or perhaps we should mark the word "Index" in red.

[mdefazio]

My thinking is that we should either make the message clear that the Index field is invalid, or perhaps we should mark the word "Index" in red.

Can we do both (and for most/all errors)? Will help if the error is further down the form.

[mdefazio]

@gmmorris From discussions with the design team, the way to solve this would be to provide something when it's empty. It's just rendering whatever is passed to it, so we have flexibility on how we make this work for us. Perhaps we have a message where the index would be (and the expression group shows red for error)?

But it's not something that makes sense to build into the component itself as we lose some of the flexibility.