Fix: Prevent HTML output during WordPress core update

Add action hook to disable async translation updates that output HTML to the console when updating WordPress core. This prevents unwanted HTML tags and JavaScript from appearing in the command line output.

The fix works by adding an early action hook (priority 1) on 'upgrader_process_complete' that removes the Language_Pack_Upgrader::async_upgrade action (priority 20) before it can execute and produce HTML output.

Co-authored-by: swissspidy <841956+swissspidy@users.noreply.github.com>

Author: Copilot

src/Core_Command.php

@@ -1213,6 +1213,15 @@ public function update( $args, $assoc_args ) {
 
 			require_once ABSPATH . 'wp-admin/includes/upgrade.php';
 
+			// Prevent async translation updates which output HTML.
+			add_action(
+				'upgrader_process_complete',
+				function () {
+					remove_action( 'upgrader_process_complete', array( 'Language_Pack_Upgrader', 'async_upgrade' ), 20 );
+				},
+				1
+			);
+
 			if ( $update->version ) {
 				WP_CLI::log( "Updating to version {$update->version} ({$update->locale})..." );
 			} else {