[improvement] Better error messages

[halilduygulu]

Hi, thanks for this library.
I recently started using and I struggled with this kind of error messages.
Is it possible to pinpoint the error messages to related column name more? Of course I see most error messages have columnnames inside but this one below, I spent a lot of time to find 1 column causing this in a 40+ column table.

[ERROR] AttributeError: 'NoneType' object has no attribute 'encode'
Traceback (most recent call last):
  File "/var/task/serverless_sdk/__init__.py", line 144, in wrapped_handler
    return user_handler(event, context)
  File "/var/task/sqs_process.py", line 65, in ingest_events
    types_check = False
  File "/var/task/clickhouse_driver/client.py", line 245, in execute
    columnar=columnar
  File "/var/task/clickhouse_driver/client.py", line 472, in process_insert_query
    types_check=types_check, columnar=columnar)
  File "/var/task/clickhouse_driver/client.py", line 524, in send_data
    self.connection.send_data(block)
  File "/var/task/clickhouse_driver/connection.py", line 554, in send_data
    self.block_out.write(block)
  File "/var/task/clickhouse_driver/streams/native.py", line 39, in write
    self.fout, types_check=block.types_check)
  File "/var/task/clickhouse_driver/columns/service.py", line 107, in write_column
    column.write_data(items, buf)
  File "/var/task/clickhouse_driver/columns/base.py", line 77, in write_data
    self._write_data(items, buf)
  File "/var/task/clickhouse_driver/columns/base.py", line 81, in _write_data
    self.write_items(prepared, buf)
  File "/var/task/clickhouse_driver/columns/stringcolumn.py", line 19, in write_items
    buf.write_strings(items, encoding=self.encoding)
  File "clickhouse_driver/bufferedwriter.pyx", line 54, in clickhouse_driver.bufferedwriter.BufferedWriter.write_strings

[WesleyBatista]

for those looking for the solution: compare the table structure with show create mytable and the data you are sending.

in my case for example it was a column of type String but I was sending a None value. ensuring you are sending an empty string instead of None or changing column type to Nullable(String) solves it.