Description

Currently, error handling must be specified on every individual step:

{
  "id": "step1",
  "onError": {"strategy": "continue"},
  ...
},
{
  "id": "step2",
  "onError": {"strategy": "continue"},
  ...
}

For flows where most steps should continue on error (e.g., document formatting, visual rendering), this creates boilerplate and is easy to miss — one step without `onError` crashes the entire flow.

Suggestion

Add a flow-level default:

{
  "key": "my-formatting-flow",
  "defaultOnError": {"strategy": "continue"},
  "steps": [
    {"id": "criticalStep", "onError": {"strategy": "fail"}, ...},
    {"id": "step2", ...},
    {"id": "step3", ...}
  ]
}

Steps inherit the flow-level default unless they explicitly override it. This:

1. Reduces boilerplate (one declaration vs N per step)
2. Prevents accidental flow crashes from missing `onError` on non-critical steps
3. Makes the error handling strategy visible at the flow level