Crash on inf value in CSV

[vlmutolo]

Describe the bug
When the value inf is found in a CSV file, the BigDecimal From<f64> implementation crashes. I haven't finished investigating, but it seems like that crate assumes all f64s can be turned into a BigDecimal. Not sure they accounted for inf values. I was going to open a PR when I found the issue, but now I''m not sure if this is better solved in the BigDecimal crate or in nu_protocol::UntaggedValue::decimal.

To Reproduce
Steps to reproduce the behavior:

1. Create the following CSV file. Name it bad.csv.

1,2
3,inf

2. Start nushell (nu).
3. Execute open bad.csv. This step should panic.

Expected behavior
I expected it to display the CSV file. It crashes instead.

Screenshots
If applicable, add screenshots to help explain your problem.

[thegedge]

Probably the same as #2349

BigDecimal can't represent infinity 😞

[vlmutolo]

Yeah, I also found that bug. Figured it was different enough (float vs int) to warrant another issue.

Good news is that there's a PR in the bigdecimal crate to at least fix the nan and inf issue. Bad news is that it doesn't look like there's been any activity since late May.

[thegedge]

I also created akubera/bigdecimal-rs#67, but if a PR has been sitting around this long, it may not end up getting addressed. If there's no movement, I think there are some other options:

1. find other crates that can represent infinity,
2. build checks to verify these special conditions, or
3. wrap these types ourselves and add the behaviour we need.