title: Cannot see error message in http response in Kotlin Fuel
body: <p>I am sending an HTTP PUT request to my Elasticsearch server using Fuel library on Kotlin. However, I cannot see an error body if the server returns 404 or 400. I am expecting to get an error message similar to the following:</p>
  
  <pre><code>{
    "error": {
      "root_cause": [
        {
          "type": "invalid_snapshot_name_exception",
          "reason": "[snap1:kopya3]Invalid snapshot name [kopya3], snapshot with the same name already exists"
        }
      ],
      "type": "invalid_snapshot_name_exception",
      "reason": "[snap1:kopya3]Invalid snapshot name [kopya3], snapshot with the same name already exists"
    },
    "status": 400
  }
  </code></pre>
  
  <p>Here's my code:</p>
  
  <pre><code>        val (request, response, result) = fullUrl
              .httpPut()
              .body(payload)
              .responseString()
  
          val (bytes, error) = result
  
          print(error)
  </code></pre>
  
  <p>Instead what I see is:</p>
  
  <pre><code>HTTP Exception 400 Bad Request
      com.github.kittinunf.fuel.core.FuelError$Companion.wrap(FuelError.kt:84)
      com.github.kittinunf.fuel.core.DeserializableKt.response(Deserializable.kt:168)
      com.github.kittinunf.fuel.core.requests.DefaultRequest.responseString(DefaultRequest.kt:475)
      com.a.b.c.d.model.Cluster.createSnapshot(Cluster.kt:67)
      com.a.b.c.d.model.Cluster.createSnapshot$default(Cluster.kt:57)
      com.a.b.c.d.model.ClusterKt.main(Cluster.kt:85)
  Caused by: HTTP Exception 400 Bad Request
      com.github.kittinunf.fuel.core.FuelError$Companion.wrap(FuelError.kt:86)
  Caused by: com.github.kittinunf.fuel.core.HttpException: HTTP Exception 400 Bad Request
      com.github.kittinunf.fuel.core.requests.RequestTask.prepareResponse(RequestTask.kt:35)
      com.github.kittinunf.fuel.core.requests.RequestTask.call(RequestTask.kt:47)
      com.github.kittinunf.fuel.core.requests.RequestTask.call(RequestTask.kt:14)
      com.github.kittinunf.fuel.core.DeserializableKt.response(Deserializable.kt:166)
      com.github.kittinunf.fuel.core.requests.DefaultRequest.responseString(DefaultRequest.kt:475)
      com.a.b.c.d.model.Cluster.createSnapshot(Cluster.kt:67)
      com.a.b.c.d.model.Cluster.createSnapshot$default(Cluster.kt:57)
      com.a.b.c.d.model.ClusterKt.main(Cluster.kt:85)
  </code></pre>
  
  <p>How can I see the actual error message? Thanks in advance.</p>