diff --git a/includes/libs/JavaScriptMinifier.php b/includes/libs/JavaScriptMinifier.php
index d87a3fdcdf..f778983c9f 100644
--- a/includes/libs/JavaScriptMinifier.php
+++ b/includes/libs/JavaScriptMinifier.php
@@ -713,12 +713,17 @@ class JavaScriptMinifier {
 			$newlineFound = false;
 
 			// Now that we have output our token, transition into the new state.
+			echo "\n| stack | " . implode('>', array_map( 'self::getConstName', $stack ) );
+			echo "\n| token: `$token`";
 			if ( isset( $push[$state][$type] ) && count( $stack ) < self::STACK_LIMIT ) {
+				echo " | action = stack_push " . self::getConstName( $push[$state][$type] );
 				$stack[] = $push[$state][$type];
 			}
 			if ( $stack && isset( $pop[$state][$type] ) ) {
+				echo " | action = stack_pop";
 				$state = array_pop( $stack );
 			} elseif ( isset( $goto[$state][$type] ) ) {
+				echo " | action = goto " . self::getConstName( $goto[$state][$type] );
 				$state = $goto[$state][$type];
 			}
 		}
@@ -729,4 +734,13 @@ class JavaScriptMinifier {
 		// TODO: Handle the error: trigger_error, throw exception, return false...
 		return false;
 	}
+
+	private static function getConstName( $constVal ) {
+		$theClass = new ReflectionClass( self::class );
+		foreach ( $theClass->getConstants() as $name => $value ) {
+			if ( $value === $constVal ) {
+				return $name;
+			}
+		}
+	}
 }