FIX issue with current PR#9 - work with Slim3

Author: llaville

src/PhpDebugBarMiddleware.php

@@ -83,13 +83,19 @@ private function getStaticFile(UriInterface $uri)
             return;
         }
 
-        $pathToFile = substr($uri->getPath(), strlen($this->debugBarRenderer->getBaseUrl()));
+        if (empty($uri->getBasePath())) {
+            return;
+        }
+
+        $path = $uri->getBasePath() ?: $uri->getPath();
+        $pathToFile = substr($path, strlen($this->debugBarRenderer->getBaseUrl()));
 
         $fullPathToFile = $this->debugBarRenderer->getBasePath() . $pathToFile;
 
         if (!file_exists($fullPathToFile)) {
             return;
         }
+        $fullPathToFile = str_replace('/', DIRECTORY_SEPARATOR, $fullPathToFile);
 
         $stream = new Stream($fullPathToFile, 'r');
         $staticResponse = new Response($stream);