diff --git a/src/wp-content/themes/twentyfourteen/inc/featured-content.php b/src/wp-content/themes/twentyfourteen/inc/featured-content.php
index b98ab983919df..3193aa8b93549 100644
--- a/src/wp-content/themes/twentyfourteen/inc/featured-content.php
+++ b/src/wp-content/themes/twentyfourteen/inc/featured-content.php
@@ -212,7 +212,7 @@ public static function delete_transient() {
 	 * @since Twenty Fourteen 1.0
 	 *
 	 * @param WP_Query $query WP_Query object.
-	 * @return WP_Query Possibly-modified WP_Query.
+	 * @return void
 	 */
 	public static function pre_get_posts( $query ) {
 
diff --git a/src/wp-content/themes/twentytwenty/inc/template-tags.php b/src/wp-content/themes/twentytwenty/inc/template-tags.php
index fdf51ccee9624..e15ae6652bbec 100644
--- a/src/wp-content/themes/twentytwenty/inc/template-tags.php
+++ b/src/wp-content/themes/twentytwenty/inc/template-tags.php
@@ -29,7 +29,7 @@
  *
  * @param array $args    Arguments for displaying the site logo either as an image or text.
  * @param bool  $display Display or return the HTML.
- * @return string Compiled HTML based on our arguments.
+ * @return string|void Compiled HTML based on our arguments.
  */
 function twentytwenty_site_logo( $args = array(), $display = true ) {
 	$logo       = get_custom_logo();
@@ -107,7 +107,7 @@ function twentytwenty_site_logo( $args = array(), $display = true ) {
  * @since Twenty Twenty 1.0
  *
  * @param bool $display Display or return the HTML.
- * @return string The HTML to display.
+ * @return string|void The HTML to display.
  */
 function twentytwenty_site_description( $display = true ) {
 	$description = get_bloginfo( 'description' );
@@ -249,7 +249,7 @@ function twentytwenty_edit_post_link( $link, $post_id, $text ) {
  *
  * @param int    $post_id  The ID of the post.
  * @param string $location The location where the meta is shown.
- * @return string Post meta HTML.
+ * @return string|void Post meta HTML.
  */
 function twentytwenty_get_post_meta( $post_id = null, $location = 'single-top' ) {
 
diff --git a/src/wp-content/themes/twentytwentyone/classes/class-twenty-twenty-one-customize.php b/src/wp-content/themes/twentytwentyone/classes/class-twenty-twenty-one-customize.php
index 53db8dffb216f..d4bc16e20171d 100644
--- a/src/wp-content/themes/twentytwentyone/classes/class-twenty-twenty-one-customize.php
+++ b/src/wp-content/themes/twentytwentyone/classes/class-twenty-twenty-one-customize.php
@@ -35,8 +35,12 @@ public function __construct() {
 		public function register( $wp_customize ) {
 
 			// Change site-title & description to postMessage.
-			$wp_customize->get_setting( 'blogname' )->transport        = 'postMessage'; // @phpstan-ignore-line. Assume that this setting exists.
-			$wp_customize->get_setting( 'blogdescription' )->transport = 'postMessage'; // @phpstan-ignore-line. Assume that this setting exists.
+			foreach ( array( 'blogname', 'blogdescription' ) as $setting_id ) {
+				$setting = $wp_customize->get_setting( $setting_id );
+				if ( $setting ) {
+					$setting->transport = 'postMessage';
+				}
+			}
 
 			// Add partial for blogname.
 			$wp_customize->selective_refresh->add_partial(
diff --git a/src/wp-content/themes/twentytwentyone/classes/class-twenty-twenty-one-dark-mode.php b/src/wp-content/themes/twentytwentyone/classes/class-twenty-twenty-one-dark-mode.php
index d5672c4054f3c..6644e7d02eeab 100644
--- a/src/wp-content/themes/twentytwentyone/classes/class-twenty-twenty-one-dark-mode.php
+++ b/src/wp-content/themes/twentytwentyone/classes/class-twenty-twenty-one-dark-mode.php
@@ -98,7 +98,7 @@ public function enqueue_scripts() {
 		if ( is_rtl() ) {
 			$url = get_template_directory_uri() . '/assets/css/style-dark-mode-rtl.css';
 		}
-		wp_enqueue_style( 'tt1-dark-mode', $url, array( 'twenty-twenty-one-style' ), wp_get_theme()->get( 'Version' ) ); // @phpstan-ignore-line. Version is always a string.
+		wp_enqueue_style( 'tt1-dark-mode', $url, array( 'twenty-twenty-one-style' ), wp_get_theme()->get( 'Version' ) );
 	}
 
 	/**
diff --git a/src/wp-content/themes/twentytwentyone/classes/class-twenty-twenty-one-svg-icons.php b/src/wp-content/themes/twentytwentyone/classes/class-twenty-twenty-one-svg-icons.php
index 398ef82bbd7c8..2a261433e4843 100644
--- a/src/wp-content/themes/twentytwentyone/classes/class-twenty-twenty-one-svg-icons.php
+++ b/src/wp-content/themes/twentytwentyone/classes/class-twenty-twenty-one-svg-icons.php
@@ -181,18 +181,17 @@ public static function get_svg( $group, $icon, $size ) {
 		 *
 		 * @since Twenty Twenty-One 1.0
 		 *
-		 * @param array $arr Array of icons.
+		 * @param array<string, string> $arr Array of icons.
 		 */
 		$arr = apply_filters( "twenty_twenty_one_svg_icons_{$group}", $arr );
 
 		$svg = '';
-		if ( array_key_exists( $icon, $arr ) ) {
+		if ( isset( $arr[ $icon ] ) && is_string( $arr[ $icon ] ) ) {
 			$repl = sprintf( '<svg class="svg-icon" width="%d" height="%d" aria-hidden="true" role="img" focusable="false" ', $size, $size );
 
-			$svg = preg_replace( '/^<svg /', $repl, trim( $arr[ $icon ] ) ); // Add extra attributes to SVG code.
+			$svg = (string) preg_replace( '/^<svg /', $repl, trim( $arr[ $icon ] ) ); // Add extra attributes to SVG code.
 		}
 
-		// @phpstan-ignore-next-line.
 		return $svg;
 	}
 
diff --git a/src/wp-content/themes/twentytwentyone/inc/template-functions.php b/src/wp-content/themes/twentytwentyone/inc/template-functions.php
index 7639331c37286..529564c295319 100644
--- a/src/wp-content/themes/twentytwentyone/inc/template-functions.php
+++ b/src/wp-content/themes/twentytwentyone/inc/template-functions.php
@@ -339,12 +339,12 @@ function twenty_twenty_one_get_non_latin_css( $type = 'front-end' ) {
 	}
 
 	// Return the specified styles.
-	return twenty_twenty_one_generate_css( // @phpstan-ignore-line.
+	return twenty_twenty_one_generate_css(
 		implode( ',', $elements[ $type ] ),
 		'font-family',
 		implode( ',', $font_family[ $locale ] ),
-		null,
-		null,
+		'',
+		'',
 		false
 	);
 }
diff --git a/src/wp-includes/class-wp-theme.php b/src/wp-includes/class-wp-theme.php
index c894f6dd72f40..a5f2459d490c7 100644
--- a/src/wp-includes/class-wp-theme.php
+++ b/src/wp-includes/class-wp-theme.php
@@ -866,6 +866,14 @@ public function cache_delete() {
 	 *
 	 * @param string $header Theme header. Name, Description, Author, Version, ThemeURI, AuthorURI, Status, Tags.
 	 * @return string|array|false String or array (for Tags header) on success, false on failure.
+	 *
+	 * @phpstan-return (
+	 *     $header is 'Tags'
+	 *         ? string[]|false
+	 *         : ( $header is 'Name'|'ThemeURI'|'Description'|'Author'|'AuthorURI'|'Version'|'Template'|'Status'|'TextDomain'|'DomainPath'|'RequiresWP'|'RequiresPHP'|'UpdateURI'
+	 *             ? string|false
+	 *             : false )
+	 * )
 	 */
 	public function get( $header ) {
 		if ( ! isset( $this->headers[ $header ] ) ) {