# `Runic.UnresolvedReferenceError`
[🔗](https://github.com/zblanco/runic/blob/main/lib/runic/exceptions.ex#L1)

Raised when a component references another component that does not exist in the workflow.

This typically occurs when adding a rule with meta expressions like `state_of(:counter)`
before the `:counter` component has been added to the workflow.

## Example

    workflow = Workflow.new()
    
    # This will raise because :counter doesn't exist yet
    |> Workflow.add(rule_using_state_of_counter)
    
    # The accumulator should be added first
    |> Workflow.add(counter_accumulator)

## Solutions

1. Add target components before adding rules that reference them
2. Ensure component names match exactly (atoms are case-sensitive)
3. For subcomponent references like `{:parent, :child}`, ensure both parent and child exist

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*Consult [api-reference.md](api-reference.md) for complete listing*