Raise ValueError on invalid response body (#119)

* Raise ValueError on empty response body

* Add log messaage on json decode ValueError

* Remove unused import from dev

* Use class logger object

dyn/core.py

@@ -287,7 +287,20 @@ def _handle_response(self, response, uri, method, raw_args, final):
         if self.poll_incomplete:
             response, body = self.poll_response(response, body)
             self._last_response = response
-        ret_val = json.loads(body.decode('UTF-8'))
+
+        if not body:
+            err_msg_fmt = "Received Empty Response: {!r} status: {!r} {!r}"
+            error_message = err_msg_fmt.format(body, response.status, uri)
+            self.logger.error(error_message)
+            raise ValueError(error_message)
+
+        json_err_fmt = "Decode Error on Response Body: {!r} status: {!r} {!r}"
+        try:
+            ret_val = json.loads(body.decode('UTF-8'))
+        except ValueError:
+            self.logger.error(json_err_fmt.format(body, response.status, uri))
+            raise
+
         if self.__call_cache is not None:
             self.__call_cache.append((uri, method, clean_args(raw_args),
                                       ret_val['status']))