Update exception thrown for invalid config

Author: benrowe

src/UrlService.php

@@ -10,7 +10,7 @@
 namespace Benrowe\Laravel\Url;
 
 use Illuminate\Http\Request;
-use Exception;
+use InvalidArgumentException as Exception;
 
 /**
  * URI Service that generates a public endpoint from the requested filesystem

tests/UrlTest.php

@@ -77,7 +77,7 @@ public function testUrl()
         $this->assertSame(null, $this->url->url('images/img.jpg', 'disabled', true));
 
         // notpublic
-        $this->setExpectedException('Exception');
+        $this->setExpectedException('InvalidArgumentException');
         $this->url->url('doesntexist', 'notpublic');
     }
 }