fix comparison for d in generateTimeSeries

src/lib/date.ts

@@ -350,7 +350,7 @@ export function generateTimeSeries(
   return timeseries.map(t => {
     const { x, y, d } = lookup.get(t) || {};
 
-    return { x: t, d: d || x, y: y ?? null };
+    return { x: t, d: d ?? x, y: y ?? null };
   });
 }