code: function inspect (p) {
      if (!isObject(p.params)) p.params = { value: p.params }
      if (p.params.error !== undefined) {
        p.params = { error: p.params.error } // discard all fields but the error field
        p.s.state = -1 // abort unless there is a handler in the stack
        while (p.s.stack.length > 0 && !p.s.stack[0].marker) {
          if ((p.s.state = p.s.stack.shift().catch || -1) >= 0) break
        }
      }
    }
docs: wrap params if not a dictionary, branch to error handler if error