Issue #3382942: Eliminate dependencies on Composer Stager internals

package_manager/src/Event/StatusCheckEvent.php

@@ -45,11 +45,12 @@ final class StatusCheckEvent extends PreOperationStageEvent {
     // examine the list of excluded paths.
     if ($excluded_paths instanceof \Throwable) {
       $this->addErrorFromThrowable($excluded_paths);
-      $this->excludedPaths = NULL;
+      $excluded_paths = NULL;
     }
     else {
-      $this->excludedPaths = new ImmutablePathList($excluded_paths);
+      $excluded_paths = new ImmutablePathList($excluded_paths);
     }
+    $this->excludedPaths = $excluded_paths;
   }
 
   /**