Changed set_file_content to accept only a regular file path.

httplib.h

@@ -5752,12 +5752,21 @@ inline void Response::set_chunked_content_provider(
 
 inline void Response::set_file_content(const std::string &path,
                                        const std::string &content_type) {
-  file_content_path_ = path;
-  file_content_content_type_ = content_type;
+  detail::FileStat stat(dir);
+  if (stat.is_file(path)) {
+    file_content_path_ = path;
+    file_content_content_type_ = content_type;
+    return;
+  }
+
+#ifndef CPPHTTPLIB_NO_EXCEPTIONS
+  std::string msg = "'" + path + "' is not a regular file.";
+  throw std::invalid_argument(msg);
+#endif
 }
 
 inline void Response::set_file_content(const std::string &path) {
-  file_content_path_ = path;
+  return set_file_content(path, std::string());
 }
 
 // Result implementation