Merge pull request #1372 from soyuka/patch-1

throw exception instead of using Panic in the TestSuite.php

src/TestSuite.php

@@ -102,7 +102,7 @@ final class TestSuite
         }
 
         if (! self::$instance instanceof self) {
-            Panic::with(new InvalidPestCommand);
+            throw new InvalidPestCommand;
         }
 
         return self::$instance;