add line number to error messages

[matt-telstra]

I just got an error when parsing a particular file. I'm not yet sure whether the file is invalid, or there's a bug in this library.

It would be nice if the error messages mentioned the line number. My particular error was pretty deep, so I've just added a try except that catches and rethrows errors.

So the original error I had was:

Traceback (most recent call last):
  File "/Users/matthew/Documents/nem12/nemreader/nem_reader.py", line 272, in parse_nem12_rows
    readings[nmi_d.nmi][nmi_d.nmi_suffix][-1] = update_reading_events(
  File "/Users/matthew/Documents/nem12/nemreader/nem_reader.py", line 504, in update_reading_events
    t_start=readings[i].t_start,
IndexError: list index out of range

Now it looks like:

Traceback (most recent call last):
  File "/Users/matthew/Documents/nem12/nemreader/nem_reader.py", line 272, in parse_nem12_rows
    readings[nmi_d.nmi][nmi_d.nmi_suffix][-1] = update_reading_events(
  File "/Users/matthew/Documents/nem12/nemreader/nem_reader.py", line 504, in update_reading_events
    t_start=readings[i].t_start,
IndexError: list index out of range

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/Users/matthew/Documents/nem12/main.py", line 9, in <module>
    df = nf.get_data_frame()
  File "/Users/matthew/Documents/nem12/nemreader/nem_reader.py", line 124, in get_data_frame
    nd = self.nem_data()
  File "/Users/matthew/Documents/nem12/nemreader/nem_reader.py", line 109, in nem_data
    reads = self.parse_nem_file(nmi_file)
  File "/Users/matthew/Documents/nem12/nemreader/nem_reader.py", line 80, in parse_nem_file
    return parse_nem12_rows(reader, file_name=nem_file)
  File "/Users/matthew/Documents/nem12/nemreader/nem_reader.py", line 285, in parse_nem12_rows
    raise ValueError(f"Unable to parse row {row_num}") from e
ValueError: Unable to parse line 3360

Which I think makes it easier to try to see what went wrong by looking at the raw file..

[aguinane]

Thanks, definitely seems like it would be helpful for large files.