Handle null values

Author: techniq

frontend/src/lib/components/charts/FeaturesLineChart.svelte

@@ -8,6 +8,7 @@
 	import { formatDate, formatValue } from '$lib/util/format';
 	import { Badge } from '../ui/badge';
 	import { isMacOS } from '$src/lib/util/browser';
+	import { NULL_VALUE } from '$src/lib/constants/common';
 
 	type LineChartProps = ComponentProps<typeof LineChart>;
 	type BrushProps = ComponentProps<Brush>;
@@ -38,7 +39,7 @@
 			data: d.points.map((p) => {
 				return {
 					date: new Date(p.ts),
-					value: p.value
+					value: p.value === NULL_VALUE ? null : p.value
 				};
 			}),
 			color: colorScale(d.feature)

frontend/src/lib/constants/common.ts

@@ -0,0 +1,2 @@
+// Maps to  `Constants.magicNullDouble` on server - https://github.com/zipline-ai/chronon/blob/main/api/src/main/scala/ai/chronon/api/Constants.scala#L87
+export const NULL_VALUE = -27980863399423856;