After entering a couple dozen costs in my board, I noticed the `summaryByLabel` calculation was displayed as `NaN` for some Labels. Some of those Labels had actual costs, and some of them had costs previously that I had removed. While stepping through the JS, it seemed like `costArray[cardIdx]` was sometimes, for example, an Array such as [null, null, null]`. This evaluates to `true`, but then `parseFloat on `null` results in `NaN`, which breaks the sum for that Label. This change avoids that result by only updating `listSums` if that cost exists for that Card.
02 16, 2020