Default behaviour rejected all rows (Records) with more or fewer columns
(Fields) than the first row, preventing them from parsing at all and
silently hiding them. While RFC4180 section 2.4 says each line _should_
contain the same number of fields, enforcing this on the viewer is
unhelpful.
This pull request disables that validation, allowing the viewer to
render lines with fewer columns than the maximum number within the file.
As it's a simple HTML table, this works without additional changes (i.e.
no need to manually determine the maximum number of columns), but the
default appearance of rows with fewer columns may be undesirable to some
people, especially when using CSS that has `td {border-right: none}`.
<img width="1408" height="156" alt="Screenshot without cell right
borders"
src="https://github.com/user-attachments/assets/d4c19bbc-3fd2-4fd1-83a6-1125e953e95b"
/>
<img width="1397" height="158" alt="Screenshot with cell right borders"
src="https://github.com/user-attachments/assets/86aaafcb-d7e8-4228-99a8-7527c823a07c"
/>
Fixes#16559, #30358.
Unfortunately, retaining empty lines is less trivial, so the line
numbers on the leftmost column will still not match the source file
whenever those are present, though a future PR could address that.
5fe3296055