fix NaN for bmi when divide-by-zero

lib/utils.ts

@@ -41,8 +41,12 @@ export function sortByDate<T>(
 
 export const bmiFromMetric = (kg: number, cm: number) => {
   const m = cm / 100;
-  const bmi = kg / (m * m);
-  return bmi ? Math.round(bmi) : NaN;
+  const m2 = m * m;
+  if (m2 === 0) {
+    return null;
+  }
+  const bmi = kg / m2;
+  return !Number.isNaN(bmi) ? Math.round(bmi) : null;
 };
 
 export function getBmiStatus(
@@ -59,7 +63,9 @@ export function getBmiStatus(
     ) || null;
   const bmi = bmiFromMetric(params.weight, params.height);
 
-  if (!thresholdByAge || Number.isNaN(bmi)) return null;
+  if (!thresholdByAge || bmi === null) {
+    return null;
+  }
 
   if (bmi > thresholdByAge.obesity_min) return BmiCategory.OBESE;
   if (bmi > thresholdByAge.strong_min) return BmiCategory.VERY_OVERWEIGHT;