Empty last column does not get mapped

[victorandree]

• Operating System: macOS 10.14
• Node Version: 11.6.0
• NPM Version: 6.7.0
• csv-parser Version: 2.1.0

Expected Behavior

I expect all values to be sent through mapValues, so I can change e.g. empty strings to null.

Actual Behavior

If the final column is empty, i.e. the final character on the line is ,, then the last value is not sent through mapValues.

How Do We Reproduce?

Save as index.js:

const csv = require('csv-parser');
const { Readable } = require('stream');

const dummy = `a,b,c
1,2,
3,4,5
6,,
`;

const s = new Readable();
s.push(dummy);
s.push(null);

const rows = [];
s.pipe(
  csv({
    mapValues: ({ value, index }) => {
      console.log(index);
      return value === '' ? null : value;
    },
  }),
)
  .on('data', row => rows.push(row))
  .on('end', () => {
    console.log(rows);
  });

Run node index.js:

0
1
0
1
2
0
1
[ Row { a: '1', b: '2', c: '' },
  Row { a: '3', b: '4', c: '5' },
  Row { a: '6', b: null, c: '' } ]

mapValues does not run for the first and final rows, leaving it as empty string. This is obviously happening because of https://github.com/mafintosh/csv-parser/blob/master/index.js#L182 simply inserting a this._empty value. Skipping mapValue for this value is not consistent with other columns.