Forms: Fix warning when post author data returns false. (#42115)

* Fix 'Attempt to read property on bool' warning.

* Changelog.

* Added a test to cover the failure.

Committed via a GitHub action: https://github.com/Automattic/jetpack/actions/runs/13633058435

Upstream-Ref: Automattic/jetpack@5964561

CHANGELOG.md

@@ -19,6 +19,7 @@ This is an alpha version! The changes listed here are not final.
 - Forms: use placeholder attribute in editor instead of value
 
 ### Fixed
+- Fix warnings when post author is not available.
 - Forms: Ensure fields that skip rendering (like empty options fields) do not trigger validation or show value in form submission response.
 - Forms: Fix 404 error when a user submits an invalid form with JavaScript disabled.
 - Forms: fix field name set as label when trying to empty label

src/contact-form/class-contact-form.php

@@ -115,7 +115,11 @@ public function __construct( $attributes, $content = null ) {
 		} elseif ( $post ) {
 			$attributes['id'] = $post->ID;
 			$post_author      = get_userdata( $post->post_author );
-			$default_to      .= $post_author->user_email;
+			if ( is_a( $post_author, '\WP_User' ) ) {
+				$default_to .= $post_author->user_email;
+			} else {
+				$default_to .= get_option( 'admin_email' );
+			}
 		}
 
 		if ( ! empty( self::$forms ) ) {
@@ -534,7 +538,8 @@ public static function get_compiled_form( $feedback_id, $form ) {
 					}
 				} else {
 					// The feedback content is stored as the first "half" of post_content
-					$value         = is_a( $feedback, '\WP_Post' ) ? $feedback->post_content : '';
+					$value         = ( is_object( $feedback ) && is_a( $feedback, '\WP_Post' ) ) ?
+									$feedback->post_content : '';
 					list( $value ) = explode( '<!--more-->', $value );
 					$value         = trim( $value );
 				}
@@ -627,7 +632,8 @@ public static function get_compiled_form_for_email( $feedback_id, $form ) {
 					}
 				} else {
 					// The feedback content is stored as the first "half" of post_content
-					$value         = is_a( $feedback, '\WP_Post' ) ? $feedback->post_content : '';
+					$value         = ( is_object( $feedback ) && is_a( $feedback, '\WP_Post' ) ) ?
+									$feedback->post_content : '';
 					list( $value ) = explode( '<!--more-->', $value );
 					$value         = trim( $value );
 				}