[6.x] Fix Invalid ISO 8601 date time string error from Date Fieldtype (#13701)

Co-authored-by: duncanmcclean <19637309+duncanmcclean@users.noreply.github.com>
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Jason Varga <jason@pixelfear.com>

Author: 3 people

resources/js/components/fieldtypes/DateFieldtype.vue

@@ -68,7 +68,7 @@ export default {
         },
 
         datePickerValue() {
-            if (!this.value) {
+            if (!this.value || this.value === 'now') {
                 return null;
             }
 

resources/js/tests/components/fieldtypes/DateFieldtype.test.js

@@ -29,7 +29,9 @@ const makeDateField = (props = {}) => {
         },
         global: {
             provide: {
-                [containerContextKey]: {}
+                [containerContextKey]: {
+                    withoutDirtying: (callback) => callback(),
+                }
             },
             mocks: {
                 $config: {
@@ -74,3 +76,9 @@ test.each([
 
     expect(dateField.vm.datePickerValue.toString()).toBe(expectedDate);
 });
+
+test('datePickerValue returns null when value is "now"', () => {
+    const dateField = makeDateField({ value: 'now' });
+
+    expect(dateField.vm.datePickerValue).toBe(null);
+});