Fix #556: remove legacy code (#557)

Author: sitingren

Diff for: vertica_python/vertica/cursor.py

@@ -154,7 +154,6 @@ def __init__(self,
         self.operation = None
         self.prepared_sql = None  # last statement been prepared
         self.prepared_name = "s0"
-        self.error = None
         self._sql_literal_adapters = {}
         self._disable_sqldata_converter = False
         self._sqldata_converters = {}
@@ -528,9 +527,6 @@ def copy(self, sql: str, data: Union[IO[AnyStr], bytes, str], **kwargs: Any) ->
             else:
                 raise errors.MessageError(f'Unexpected message: {message}')
 
-        if self.error is not None:
-            raise self.error
-
     def object_to_sql_literal(self, py_obj: Any) -> str:
         """Returns the SQL literal string converted from a Python object."""
         return self.object_to_string(py_obj, False)