[6.x] Resolve Cascade content closure before checking content (#14502)

Author: marcorieser

src/View/Cascade.php

@@ -154,14 +154,14 @@ protected function hydrateGlobals()
 
     protected function hydrateContent()
     {
-        if (! $this->content) {
-            return $this;
-        }
-
         if ($this->content instanceof \Closure) {
             $this->content = call_user_func($this->content);
         }
 
+        if (! $this->content) {
+            return $this;
+        }
+
         $variables = $this->content instanceof Augmentable
             ? $this->content->toDeferredAugmentedArray()
             : $this->content->toArray();