fix: Validate config only after the options have been set

To avoid an exception when default options are not valid but the new options are.

tests/ConfigTest.php

@@ -41,6 +41,20 @@ class ConfigTest extends BaseTest
         $this->assertConfig($config);
     }
 
+    /**
+     * Test the getInstance function.
+     *
+     * @return void
+     */
+    public function testGetInstanceFromScratch()
+    {
+        Config::destroyInstance();
+
+        $config = Config::getInstance();
+        $this->assertEquals($config->convert, false);
+        $this->assertConfig($config);
+    }
+
     /**
      * Assert that a Config object is correctly instantiated.
      *