Send a warning in case Jetpack is pinned but the pinned version is no…

…t available anymore (#5093)

* Send a warning in case Jetpack is pinned but the pinned version is not available anymore

jetpack.php

@@ -1,5 +1,4 @@
 <?php
-
 /**
  * Plugin Name: Jetpack
  * Plugin URI: https://jetpack.com
@@ -596,6 +595,13 @@ function vip_jetpack_load() {
 
 			// We should break even if we failed to load Jetpack, because some constants like JETPACK_VERSION were probably already set
 			break;
+
+			// Trigger a E_USER_WARNING in non-production environments if the pinned version could not be loaded.
+		} elseif ( ! file_exists( $path ) && defined( 'VIP_JETPACK_PINNED_VERSION' ) && wp_in( constant( 'VIP_JETPACK_PINNED_VERSION' ), $path ) ) {
+			if ( ! defined( 'VIP_GO_APP_ENVIRONMENT' ) || 'production' !== constant( 'VIP_GO_APP_ENVIRONMENT' ) ) {
+				// phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
+				trigger_error( 'Jetpack loading error: ' . constant( 'VIP_JETPACK_PINNED_VERSION' ) . ' could not be loaded, loading ' . constant( 'VIP_JETPACK_DEFAULT_VERSION' ) . ' instead.', E_USER_WARNING );
+			}
 		}
 	}