Merge pull request #137 from jackmu95/rewind-error-fix

Make sure stream is seekable before using `rewind()`

Author: reinink

src/Server.php

@@ -439,7 +439,9 @@ public function outputImage($path, array $params)
 
         $stream = $this->cache->readStream($path);
 
-        rewind($stream);
+        if (ftell($stream) !== 0) {
+            rewind($stream);
+        }
         fpassthru($stream);
         fclose($stream);
     }