Batch Trend takes into account batches that have votes but a batch breakdown of N/A

[drimgere]

Describe the bug

The Batch Trend column counts against all votes that come in, even if there is an update where there was a vote change but no breakdown of the batch re: Trump vs Biden

To Reproduce
Steps to reproduce the behavior:

1. Go to https://alex.github.io/nyt-2020-election-scraper/battleground-state-changes.html#
2. Scroll down to the North Carolina entries
3. 3 of the bottom 5 entries for North Carolina have data in the "Change" column, but in the "Batch Breakdown" column the entry is "N/A". The three entries read 220, 1,989 and 2,233 respectively.
4. Since there is no "Batch Breakdown", the "Batch Trend" column entry is empty, which is correct.
5. On the very next update with a breakdown. (6th from the bottom) There is a "Change" of 390 and a "Batch Breakdown" of Trump 46.7% / 53.3% Biden. However in the "Batch Trend" column the entry reads "Biden is averaging 4.3%" instead of lining up with the "Batch Breakdown" entry.
6. I think what's happening is that the calculation is taking the sum of all the votes in the "Changes" column and treats a value of N/A in the "Batch Breakdown" column as 0.

EDIT: I see in https://github.com/alex/nyt-2020-election-scraper/blob/master/print-battleground-state-changes that it is only the last 5 or the last 30k votes that is counted, so my calculation below has one extra row, however that row is 0 so it does not invalidate the issue brought up.

Calculation:

Votes from the "Changes" column for the bottom 6 entries that have:
0+ 220 + 0 + 1989 + 2233 + 390 = 4832

Votes for Biden calculated from the "Batch Breakdown" entry for the bottom 6 entries:
00 + 2200 + 00 + 19890 + 22330 + 39053.3% = 207

Biden Votes / Total Votes from "Changes"
207/4832 = 4.3% (4.2839%)

Expected behavior
A batch of votes shouldn't be counted towards the Batch Trend if it doesn't have a valid Batch Breakdown (i.e. not "N/A") value.

e.g. the Batch Trend for the row sixth from the bottom should read "Biden is averaging 53.3%" as the first entry that has a valid Batch Breakown

EDIT: I believe the issue is at https://github.com/alex/nyt-2020-election-scraper/blob/master/print-battleground-state-changes#L146

Screenshots

Desktop (please complete the following information):

• OS: Windows 10
• Browser Firefox/Chrome/IE
• Latest

Additional context
North Carolina has the easiest/clearest example of this error. This problem occurs in the Batch Trend for other states as well so it's a systemic calculation issue.

Thanks for your hard work!