One error struct for both the text and binary pipelines, so a caller never has to special-case which one produced it. Wraps Ichor.Error verbatim for the text side (including its caret-annotated context_lines, useful for CLI/log output); the binary side has no source text to annotate, so it only ever carries a message, a byte offset, and a stage.

Also the channel for schema-violation errors: those come back with stage: :action, the same stage Ichor.Error already uses for Ichor.Actions-level failures (a handle_rule/3/handle_token/3 callback returning {:error, _}) — so a schema violation and a syntax error are indistinguishable by shape alone, and a caller only ever needs to check {:error, %Dextrin.Error{}}.