delete the old cache only if the kernel hasn't booted yet

AsyncKernel.php

@@ -46,16 +46,15 @@ public function boot()
     {
         if (!$this->booted) {
             $this->uid = $this->generateUID();
-        }
-
-        $fs = new Filesystem();
-        // AsyncKernel loads the container only once when it loads. Storing it in the filesystem is not for cache purposes
-        // but more for using the same loading process as Kernel class use.
-        // Hence, everytime before AsyncKernel initiates the container it deletes the cache dir,
-        // to make sure it is building the updated kernel
-        $cachePath = $this->getCacheDir();
-        if ($fs->exists($cachePath)) {
-            $fs->remove($cachePath);
+            $fs = new Filesystem();
+            // AsyncKernel loads the container only once when it loads. Storing it in the filesystem is not for cache purposes
+            // but more for using the same loading process as Kernel class use.
+            // Hence, everytime before AsyncKernel initiates the container it deletes the cache dir,
+            // to make sure it is building the updated kernel
+            $cachePath = $this->getCacheDir();
+            if ($fs->exists($cachePath)) {
+                $fs->remove($cachePath);
+            }
         }
 
         parent::boot();