Multithreaded parsing error should be warning

[adienes]

┌ Error: Multi-threaded parsing failed (are there newlines inside quoted fields?), falling back to single-threaded parsing

This still returns a parsed CSV file just fine and doesn't crash the program. I think this should display as a warning and not an error

[quinnj]

cc: @Liozou

[Liozou]

Thank you for reporting this! Would it be possible for you to share the offending CSV?

I put this as an error precisely to get this kind CSVs reported here. There should indeed be no apparent issue/crash since a fallback was implemented, but it signals a possible mistake in the code and in any case it causes a severe performance drop for CSV parsing (since it falls back to a single thread).
I guess it should be displayed as a warning instead of an error when we can internally check that the cause of this is well-known (i.e. newlines inside quoted fields) and there is nothing more to be done than let the user know of the expected performance loss.

[adienes]

DKWinners_20230603.csv

sure, here is an example of such a CSV. these are results from sports betting contests. let me know if it helps!

[Liozou]

The root issue is that starting from line 30 (Gummypecs (2/3)), each line only contains 10 columns instead of 12, i.e. there should be two more commas at the end of each line. But the @error message is quite misleading here I agree, I'll try to fix that.

[adienes]

cool! thank you for the quick responses

[adienes]

btw this is not fixed for me :)

maybe it is because I set silencewarnings = true, so it is never true that numwarnings[] > 0 ?

[Liozou]

I think this is just because the latest released version of CSV.jl does not include the bugfix. You can try to ]dev CSV just to check that the bug is indeed fixed. @quinnj would you mind tagging a new patch version?
Otherwise, in the code, both versions of the warnings are under the condition that !ctx.silencewarnings so nothing should appear, unless I'm missing something...