Revert "Simplify error parsing now that we don't support <2.0 errors"

This reverts commit a6d896b.

Author: polyfractal

src/Elasticsearch/Connections/Connection.php

@@ -667,22 +667,36 @@ private function tryDeserialize500Error($response)
     private function tryDeserializeError($response, $errorClass)
     {
         $error = $this->serializer->deserialize($response['body'], $response['transfer_stats']);
-        if (is_array($error) === true && isset($error['error']['root_cause']) === true) {
-            // Try to use root cause first (only grabs the first root cause)
-            $root = $error['error']['root_cause'];
-            if (isset($root) && isset($root[0])) {
-                $cause = $root[0]['reason'];
-                $type = $root[0]['type'];
-            } else {
-                $cause = $error['error']['reason'];
-                $type = $error['error']['type'];
+        if (is_array($error) === true) {
+            // 2.0 structured exceptions
+            if (isset($error['error']['reason']) === true) {
+
+                // Try to use root cause first (only grabs the first root cause)
+                $root = $error['error']['root_cause'];
+                if (isset($root) && isset($root[0])) {
+                    $cause = $root[0]['reason'];
+                    $type = $root[0]['type'];
+                } else {
+                    $cause = $error['error']['reason'];
+                    $type = $error['error']['type'];
+                }
+
+                $original = new $errorClass($response['body'], $response['status']);
+
+                return new $errorClass("$type: $cause", $response['status'], $original);
+            } elseif (isset($error['error']) === true) {
+                // <2.0 semi-structured exceptions
+                $original = new $errorClass($response['body'], $response['status']);
+
+                return new $errorClass($error['error'], $response['status'], $original);
             }
 
-            $original = new $errorClass($response['body'], $response['status']);
-            return new $errorClass("$type: $cause", $response['status'], $original);
+            // <2.0 "i just blew up" nonstructured exception
+            // $error is an array but we don't know the format, reuse the response body instead
+            return new $errorClass($response['body'], $response['status']);
         }
 
-        // Response mangled or unexpected, just return the body
+        // <2.0 "i just blew up" nonstructured exception
         return new $errorClass($response['body']);
     }
 }