docstr: Wrapper around iterating through `self.data` (CSV source).
  
  When a CSV error is raised, we check for specific
  error messages that allow us to customize the
  error message displayed to the user.
  
  Parameters
  ----------
  row_num: int
      The row number of the line being parsed.
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code: def _next_iter_line(self, row_num: int) -> list[Scalar] | None:
      """
      Wrapper around iterating through `self.data` (CSV source).
  
      When a CSV error is raised, we check for specific
      error messages that allow us to customize the
      error message displayed to the user.
  
      Parameters
      ----------
      row_num: int
          The row number of the line being parsed.
      """
      try:
          assert not isinstance(self.data, list)
          line = next(self.data)
          # lie about list[str] vs list[Scalar] to minimize ignores
          return line  # type: ignore[return-value]
      except csv.Error as e:
          if self.on_bad_lines in (
              self.BadLineHandleMethod.ERROR,
              self.BadLineHandleMethod.WARN,
          ):
              msg = str(e)
  
              if "NULL byte" in msg or "line contains NUL" in msg:
                  msg = (
                      "NULL byte detected. This byte "
                      "cannot be processed in Python's "
                      "native csv library at the moment, "
                      "so please pass in engine='c' instead"
                  )
  
              if self.skipfooter > 0:
                  reason = (
                      "Error could possibly be due to "
                      "parsing errors in the skipped footer rows "
                      "(the skipfooter keyword is only applied "
                      "after Python's csv library has parsed "
                      "all rows)."
                  )
                  msg += ". " + reason
  
              self._alert_malformed(msg, row_num)
          return None
  
imports: from __future__ import annotations
  from collections import abc, defaultdict
  import csv
  from io import StringIO
  import re
  from typing import IO, TYPE_CHECKING, DefaultDict, Literal, cast
  import warnings
  import numpy
  from pandas._libs import lib
  from pandas.errors import EmptyDataError, ParserError, ParserWarning
  from pandas.util._decorators import cache_readonly
  from pandas.util._exceptions import find_stack_level
  from pandas.core.dtypes.common import is_bool_dtype, is_integer, is_numeric_dtype
  from pandas.core.dtypes.inference import is_dict_like
  from pandas.io.common import dedup_names, is_potential_multi_index
  from pandas.io.parsers.base_parser import ParserBase, parser_defaults
label_desc: Use image node_id 17 for calling the PythonParser obj's underlying member method code with example usage: obj._next_iter_line(row_num) and returns: line, None