Corrected YAML file parsing

* Fixes #2323.
* YAML file parsing will now properly catch and display warnings when unable to read a file.
Thanks to @CairoLee!

3rdparty/yaml-cpp/src/parse.cpp

@@ -31,7 +31,7 @@ Node Load(std::istream& input) {
 
 Node LoadFile(const std::string& filename) {
   std::ifstream fin(filename.c_str());
-  if (!fin) {
+  if (fin.bad()) {
     throw BadFile();
   }
   return Load(fin);