Error resource - is specification correct for "error_values"?

Error resource specifies that the “error_values” field returns an array of objects e.g.

"error_values" : [
    {
      "{argument}" : "{value}"
    }
 ]

Is this correct or a typo? It would seem more logical if this just be a series of objects (key/values):

"error_values" : {
  "{argument}" : "{value}"
  ...
}

This would seem to be more logical and would fit with other substituted constants (e.g. filing history descriptions etc.).