More type hints

src/Monolog/Formatter/JsonFormatter.php

@@ -163,17 +163,12 @@ class JsonFormatter extends NormalizerFormatter
      * Normalizes given exception with or without its own stack trace based on
      * `includeStacktraces` property.
      *
-     * @param Exception|Throwable $e
+     * @param Throwable $e
      *
      * @return array
      */
-    protected function normalizeException($e)
+    protected function normalizeException(\Throwable $e)
     {
-        // TODO 2.0 only check for Throwable
-        if (!$e instanceof Exception && !$e instanceof \Throwable) {
-            throw new \InvalidArgumentException('Exception/Throwable expected, got '.gettype($e).' / '.get_class($e));
-        }
-
         $data = array(
             'class' => get_class($e),
             'message' => $e->getMessage(),