[FEATURE] Step level error handling

**Is your feature request related to a problem? Please describe.**
For a given step, I want to be able to specify a step that is run when an unhandled error occurs.

**Describe the solution you'd like**
In the step settings, I'd enter the name of an existing step to run on error. (Or just enter a name and it's my responsibility to ensure the step exists.) The step specified would ONLY be called when the specific steps throws an unhandled error.

**Do you have a workaround?**
No.

**Comparable features in other tools?**
N/A I believe.

**Additional context**
I'd also like to have this for workflows, but as Dylan said in chat, there's already support that's going to be simplified later.