fix config:cache issue

Modules/Core/Config/core.php

@@ -169,4 +169,11 @@ return [
     |--------------------------------------------------------------------------
     */
     'enable-theme-overrides' => false,
+
+    /*
+    |--------------------------------------------------------------------------
+    | Check if asgard was installed
+    |--------------------------------------------------------------------------
+    */
+    'is_installed' => env('INSTALLED', false)
 ];

Modules/Core/Providers/CoreServiceProvider.php

@@ -69,7 +69,7 @@ class CoreServiceProvider extends ServiceProvider
     public function register()
     {
         $this->app->singleton('asgard.isInstalled', function () {
-            return true === env('INSTALLED', false);
+            return true === config('asgard.core.core.is_installed');
         });
         $this->app->singleton('asgard.onBackend', function () {
             return $this->onBackend();

config/asgard/core/core.php

@@ -169,4 +169,11 @@ return [
     |--------------------------------------------------------------------------
     */
     'enable-theme-overrides' => false,
+
+    /*
+    |--------------------------------------------------------------------------
+    | Check if asgard was installed
+    |--------------------------------------------------------------------------
+    */
+    'is_installed' => env('INSTALLED', false)
 ];