`comment_form()` expects optional "email" field to be passed.

[Mat Lipe]

Ticket #47975 introduced a requirement to the comment_form template tag of a passed field['email'] argument.

When using comment_form without passing field['email'] to the $args parameter you get the following notice level error.

Undefined index: email
\wp-includes\comment-template.php:2440

I have confirmed the issue does not exist on WP 5.2.4.

I have included a patch which simply checks for the existence of the email array key before using it.

[Mat Lipe]

Patch the /wp-includes/comment-template.php file

[Mat Lipe]

I should point out this only happens when the fields is provided as an argument without the "email" key. If you do not provided fields the defaults fill in the "email" key for you and this error does not occur.

[SergeyBiryukov]

In 46885:

Comments: Avoid a PHP notice in comment_form() if the email field is not set.

Follow-up to [46090].

Props mat-lipe.
Fixes #48943.

[SergeyBiryukov]

In 46886:

Comments: Avoid a PHP notice in comment_form() if the email field is not set.

Follow-up to [46090].

Props mat-lipe.
Merges [46885] to the 5.3 branch.
Fixes #48943.

[audrasjb]

Refreshed patch against trunk

[audrasjb]

Ah nice, thanks Sergey, you beat me by committing it directly :D

@mat-lipe welcome to WordPress Trac and thank you for your patch!

Please note that the patch should be generated against trunk/wordpress-develop. Here is the GitHub mirror to clone wordpress-develop sources: ​https://github.com/WordPress/wordpress-develop :-)