Fix test failure in wasmfs.test_unistd_close_rawfs

Author: kleisauke

system/lib/wasmfs/backends/node_backend.cpp

@@ -278,7 +278,8 @@ class NodeDirectory : public Directory {
 
   Directory::MaybeEntries getEntries() override {
     std::vector<Directory::Entry> entries;
-    int err = _wasmfs_node_readdir(state.path.c_str(), &entries);
+    auto currPath = state.path.empty() ? "." : state.path;
+    int err = _wasmfs_node_readdir(currPath.c_str(), &entries);
     if (err) {
       return {-err};
     }