Bug/when US phone is not included as a merge field in a Mailchimp form it causes fatal error on submission

[MaxwellGarceau]

Description of the Change

Fixed a bug causing a fatal PHP error when:

• Phone number is set to US style in the Mailchimp account
• Phone number is NOT included as a merge field in the WP plugin

us-phone-fatal-error-when-merge-field-not-included.mov

Closes #103

How to test the Change

The video us-phone-fatal-error-when-merge-field-not-included.mov above can be used as a guide for recreating the testing conditions. However, instead of a fatal error you should see a successful form submission.

Phone number

1. Set the phone format in the test Mailchimp account (/lists/settings/merge-tags) to US style
2. Select the "Update List" button to refresh the Mailchimp data with WP
3. Ensure that Phone Number is not an included merge field. The error will only occur when Phone Number is not included in the form.
4. Submit a form submission using only email (any merge field is okay and the error should occur regardless)
5. The form submission should submit successfully

Address

I added a conditional check to ensure address fields were included for submission.

With address

1. Include address in the Mailchimp admin
2. Fill out and submit a form
3. The form submission should be successful

Without address

1. Ensure that address is NOT included in the Mailchimp admin
2. Fill out and submit a form
3. The form submission should be successful

Changelog Entry

Fixed - Fatal PHP error that would occur when the phone merge field was set to US format, but the merge field was not included in the Mailchimp plugin.

Credits

Props @MaxwellGarceau

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added tests to cover my change. Small change, not worth writing tests
• All new and existing tests pass.

[qasumitbagthariya]

QA Update ✅

---

I have verified this PR in the bug/us-phone-not-included-in-mailchimp-form-causes-fatal-error-on-submission branch which has been fixed and is functioning as intended.

Screen.Recording.2025-01-16.at.7.20.45.PM.mov

Testing Environment

• WordPress: 6.7.1
• Theme: Twenty Twenty-Four 1.3
• WooCommerce - 9.5.1
• PHP: 8.0.30
• Web Server: Nginx 1.20.2
• Browser: Chrome
• OS: macOS 15.2
• Branch: bug/us-phone-not-included-in-mailchimp-form-causes-fatal-error-on-submission

Steps to Test- As mentioned in the PR description.
Test Results - It is working as expected.
Functional Demo / Screencast -
Special Notes - Ready for code review (Woo)
Testing Document status:
Cases related to this Issue/PR are added to the Critical Flow Wiki pages:

• Yes
• Not Required/Applicable for this PR

---

[qasumitbagthariya]

Regression / Smoke Test Report ✅

Tested with the smoke-testing branch, it works as expected, similar to the fix-specific branch.

Testing Environment

• WordPress: 6.7.1
• Theme: Twenty Twenty-Four 1.3
• WooCommerce - 9.5.1
• PHP: 8.0.30
• Web Server: Nginx 1.20.2
• Browser: Chrome
• OS: macOS 15.2
• Branch: smoke-testing