Fix generate error when macroable class has a "fake" method (#1066)

src/Alias.php

@@ -17,6 +17,7 @@ use Barryvdh\Reflection\DocBlock\Serializer as DocBlockSerializer;
 use Barryvdh\Reflection\DocBlock\Tag\MethodTag;
 use Closure;
 use Illuminate\Config\Repository as ConfigRepository;
+use Illuminate\Support\Facades\Facade;
 use ReflectionClass;
 
 class Alias
@@ -202,6 +203,10 @@ class Alias
     {
         $facade = $this->facade;
 
+        if (!is_subclass_of($facade, Facade::class)) {
+            return;
+        }
+
         if (!method_exists($facade, 'fake')) {
             return;
         }