Return "invalid date" when date is not formatted correctly. Stopping …

…the blank screen error

src/lib/intlFormat.test.ts

@@ -185,6 +185,14 @@ describe('intlFormat', () => {
 
       expect(date).toBeNull();
     });
+
+    it('returns if month is null', () => {
+      const date = dateFromParts(0, 0, 2000, locale);
+
+      expect(date).toBe(
+        'Invalid Date - you specified 0 (of type number) as a month, which is invalid',
+      );
+    });
   });
   //this test often fails locally. It passes on github.
   describe('dateTimeFormat', () => {

src/lib/intlFormat.ts

@@ -89,8 +89,16 @@ export const dateFromParts = (
   }
 
   if (typeof year === 'number') {
-    return dateFormat(DateTime.local(year, month, day), locale);
+    const date = DateTime.local(year, month, day);
+    if (date.invalidReason || date.invalidExplanation) {
+      return `Invalid Date - ${date.invalidExplanation}`;
+    }
+    return dateFormat(date, locale);
   } else {
+    const date = DateTime.local().set({ month, day });
+    if (date.invalidReason || date.invalidExplanation) {
+      return `Invalid Date - ${date.invalidExplanation}`;
+    }
     return dayMonthFormat(day, month, locale);
   }
 };