Update PackageManifest.php

src/Illuminate/Foundation/PackageManifest.php

@@ -113,7 +113,9 @@ class PackageManifest
         $packages = [];
 
         if ($this->files->exists($path = $this->vendorPath.'/composer/installed.json')) {
-            $packages = json_decode($this->files->get($path), true);
+            $installed = json_decode($this->files->get($path), true);
+
+            $packages = $installed['packages'] ?? $installed;
         }
 
         $ignoreAll = in_array('*', $ignore = $this->packagesToIgnore());
@@ -172,4 +174,4 @@ class PackageManifest
             $this->manifestPath, '<?php return '.var_export($manifest, true).';'
         );
     }
-}
+}
\ No newline at end of file