diff --git a/wp-admin/edit.php b/wp-admin/edit.php
index 2b917b994d..bd537bd49e 100644
--- a/wp-admin/edit.php
+++ b/wp-admin/edit.php
@@ -154,7 +154,7 @@ if ( $doaction ) {
 			}
 			$sendback = add_query_arg( 'untrashed', $untrashed, $sendback );
 
-			remove_filter( 'wp_untrash_post_status', 'wp_untrash_post_set_previous_status', 10, 3 );
+			remove_filter( 'wp_untrash_post_status', 'wp_untrash_post_set_previous_status', 10 );
 
 			break;
 		case 'delete':
diff --git a/wp-admin/includes/class-wp-list-table.php b/wp-admin/includes/class-wp-list-table.php
index 535f5d5f81..2cae7f695a 100644
--- a/wp-admin/includes/class-wp-list-table.php
+++ b/wp-admin/includes/class-wp-list-table.php
@@ -207,12 +207,14 @@ class WP_List_Table {
 	 * @since 4.0.0
 	 *
 	 * @param string $name Property to check if set.
-	 * @return bool Whether the property is set.
+	 * @return bool Whether the property is a back-compat property and it is set.
 	 */
 	public function __isset( $name ) {
 		if ( in_array( $name, $this->compat_fields, true ) ) {
 			return isset( $this->$name );
 		}
+
+		return false;
 	}
 
 	/**
@@ -313,6 +315,8 @@ class WP_List_Table {
 		if ( isset( $this->_pagination_args[ $key ] ) ) {
 			return $this->_pagination_args[ $key ];
 		}
+
+		return 0;
 	}
 
 	/**
diff --git a/wp-includes/class-wp-http-curl.php b/wp-includes/class-wp-http-curl.php
index 9b6e0eb10b..64ff7efb83 100644
--- a/wp-includes/class-wp-http-curl.php
+++ b/wp-includes/class-wp-http-curl.php
@@ -307,7 +307,7 @@ class WP_Http_Curl {
 		);
 
 		// Handle redirects.
-		$redirect_response = WP_HTTP::handle_redirects( $url, $parsed_args, $response );
+		$redirect_response = WP_Http::handle_redirects( $url, $parsed_args, $response );
 		if ( false !== $redirect_response ) {
 			return $redirect_response;
 		}
diff --git a/wp-includes/class-wp-http-streams.php b/wp-includes/class-wp-http-streams.php
index 95ff2a1a20..d6cfc53359 100644
--- a/wp-includes/class-wp-http-streams.php
+++ b/wp-includes/class-wp-http-streams.php
@@ -470,6 +470,6 @@ class WP_Http_Streams {
  * @since 2.7.0
  * @deprecated 3.7.0 Please use WP_HTTP::request() directly
  */
-class WP_HTTP_Fsockopen extends WP_HTTP_Streams {
+class WP_HTTP_Fsockopen extends WP_Http_Streams {
 	// For backward compatibility for users who are using the class directly.
 }
diff --git a/wp-includes/post.php b/wp-includes/post.php
index 1adc89908a..2487e5b4c2 100644
--- a/wp-includes/post.php
+++ b/wp-includes/post.php
@@ -5506,6 +5506,8 @@ function get_page_by_path( $page_path, $output = OBJECT, $post_type = 'page' ) {
 	if ( $foundid ) {
 		return get_post( $foundid, $output );
 	}
+
+	return null;
 }
 
 /**
@@ -5563,6 +5565,8 @@ function get_page_by_title( $page_title, $output = OBJECT, $post_type = 'page' )
 	if ( $page ) {
 		return get_post( $page, $output );
 	}
+
+	return null;
 }
 
 /**
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 2dc15dcd63..3b63098d48 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.9-alpha-51849';
+$wp_version = '5.9-alpha-51850';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.
diff --git a/wp-includes/widgets.php b/wp-includes/widgets.php
index 10f5017957..de15317d1b 100644
--- a/wp-includes/widgets.php
+++ b/wp-includes/widgets.php
@@ -1739,11 +1739,12 @@ function wp_widget_rss_process( $widget_rss, $check_feed = true ) {
 	$show_summary = isset( $widget_rss['show_summary'] ) ? (int) $widget_rss['show_summary'] : 0;
 	$show_author  = isset( $widget_rss['show_author'] ) ? (int) $widget_rss['show_author'] : 0;
 	$show_date    = isset( $widget_rss['show_date'] ) ? (int) $widget_rss['show_date'] : 0;
+	$error        = false;
+	$link         = '';
 
 	if ( $check_feed ) {
-		$rss   = fetch_feed( $url );
-		$error = false;
-		$link  = '';
+		$rss = fetch_feed( $url );
+
 		if ( is_wp_error( $rss ) ) {
 			$error = $rss->get_error_message();
 		} else {
diff --git a/wp-includes/widgets/class-wp-widget-tag-cloud.php b/wp-includes/widgets/class-wp-widget-tag-cloud.php
index fb17e69a16..52b06d9b60 100644
--- a/wp-includes/widgets/class-wp-widget-tag-cloud.php
+++ b/wp-includes/widgets/class-wp-widget-tag-cloud.php
@@ -53,6 +53,8 @@ class WP_Widget_Tag_Cloud extends WP_Widget {
 			}
 		}
 
+		$default_title = $title;
+
 		$show_count = ! empty( $instance['count'] );
 
 		$tag_cloud = wp_tag_cloud(
diff --git a/wp-mail.php b/wp-mail.php
index 1d5fbedf03..c3f921ad69 100644
--- a/wp-mail.php
+++ b/wp-mail.php
@@ -77,6 +77,9 @@ for ( $i = 1; $i <= $count; $i++ ) {
 	$content_transfer_encoding = '';
 	$post_author               = 1;
 	$author_found              = false;
+	$post_date                 = null;
+	$post_date_gmt             = null;
+
 	foreach ( $message as $line ) {
 		// Body signal.
 		if ( strlen( $line ) < 3 ) {