[dotnet] Treat unsuccessful http responses as errored commands (#13608)

* Update HttpCommandExecutor.cs

* Parse only if json

* Added guards for NullRefException

dotnet/src/webdriver/Remote/HttpCommandExecutor.cs

@@ -309,14 +309,21 @@ private Response CreateResponse(HttpResponseInfo responseInfo)
         {
             Response response = new Response();
             string body = responseInfo.Body;
-            if (responseInfo.ContentType != null && responseInfo.ContentType.StartsWith(JsonMimeType, StringComparison.OrdinalIgnoreCase))
+            if ((int)responseInfo.StatusCode < 200 || (int)responseInfo.StatusCode > 299)
             {
-                response = Response.FromJson(body);
+                if (responseInfo.ContentType != null && responseInfo.ContentType.StartsWith(JsonMimeType, StringComparison.OrdinalIgnoreCase))
+                {
+                    response = Response.FromErrorJson(body);
+                }
+                else
+                {
+                    response.Status = WebDriverResult.UnhandledError;
+                    response.Value = body;
+                }
             }
-            else if (responseInfo.StatusCode.ToString().First() != '2')
+            else if (responseInfo.ContentType != null && responseInfo.ContentType.StartsWith(JsonMimeType, StringComparison.OrdinalIgnoreCase))
             {
-                response.Status = WebDriverResult.UnhandledError;
-                response.Value = body;
+                response = Response.FromJson(body);
             }
             else
             {

dotnet/src/webdriver/Response.cs

@@ -102,10 +102,6 @@ private Response(Dictionary<string, object> rawResponse)
                         this.responseValue = valueDictionary["value"];
                     }
                 }
-                else if (valueDictionary.ContainsKey("error"))
-                {
-                    this.responseStatus = WebDriverError.ResultFromError(valueDictionary["error"].ToString());
-                }
             }
         }
 
@@ -148,6 +144,44 @@ public static Response FromJson(string value)
             return response;
         }
 
+        /// <summary>
+        /// Returns a new <see cref="Response"/> from a JSON-encoded string.
+        /// </summary>
+        /// <param name="value">The JSON string to deserialize into a <see cref="Response"/>.</param>
+        /// <returns>A <see cref="Response"/> object described by the JSON string.</returns>
+        public static Response FromErrorJson(string value)
+        {
+            Dictionary<string, object> deserializedResponse = JsonConvert.DeserializeObject<Dictionary<string, object>>(value, new ResponseValueJsonConverter());
+
+            var response = new Response();
+
+            if (!deserializedResponse.TryGetValue("value", out var valueObject))
+            {
+                throw new WebDriverException($"The 'value' property was not found in the response:{Environment.NewLine}{value}");
+            }
+
+            if (valueObject is not Dictionary<string, object> valueDictionary)
+            {
+                throw new WebDriverException($"The 'value' property is not a dictionary of <string, object>{Environment.NewLine}{value}");
+            }
+
+            response.Value = valueDictionary;
+
+            if (!valueDictionary.TryGetValue("error", out var errorObject))
+            {
+                throw new WebDriverException($"The 'value > error' property was not found in the response:{Environment.NewLine}{value}");
+            }
+
+            if (errorObject is not string)
+            {
+                throw new WebDriverException($"The 'value > error' property is not a string{Environment.NewLine}{value}");
+            }
+
+            response.Status = WebDriverError.ResultFromError(errorObject.ToString());
+
+            return response;
+        }
+
         /// <summary>
         /// Returns this object as a JSON-encoded string.
         /// </summary>