fix(localize): empty dates should be formatted as empty string

Author: tlouisse

packages/localize/src/date/formatDate.js

@@ -10,7 +10,7 @@ import { normalizeDate } from './normalizeDate.js';
  */
 export function formatDate(date, options) {
   if (!(date instanceof Date)) {
-    return '0000-00-00';
+    return '';
   }
   const formatOptions = options || {};
   // make sure months and days are always 2-digits

packages/localize/test/date/formatDate.test.js

@@ -108,8 +108,8 @@ describe('formatDate', () => {
     expect(formatDate(parsedDate, options)).to.equal('maandag 01 januari 1940');
   });
 
-  it('returns a zero-date when input is not a Date object', async () => {
+  it('returns empty string when input is not a Date object', async () => {
     const date = '1-1-2016';
-    expect(formatDate(date)).to.equal('0000-00-00');
+    expect(formatDate(date)).to.equal('');
   });
 });