Add sanity check in case no path

Author: luc-github

esp3d/src/modules/http/handlers/handle-SD-files.cpp

@@ -75,7 +75,9 @@ void HTTP_Server::handleSDFileList() {
 
   // get current path
   if (_webserver->hasArg("path")) {
-    path += _webserver->arg("path");
+    path = _webserver->arg("path");
+  } else {
+    path = "/";
   }
   // to have a clean path
   path.trim();

esp3d/src/modules/http/handlers/handle-files.cpp

@@ -63,7 +63,9 @@ void HTTP_Server::handleFSFileList() {
   }
   // get current path
   if (_webserver->hasArg("path")) {
-    path += _webserver->arg("path");
+    path = _webserver->arg("path");
+  } else {
+    path = "/";
   }
   // to have a clean path
   path.trim();