handle missing language in highlight

srchighlight.hpp

@@ -209,7 +209,16 @@ class gnu_highlighter {
             const std::string &lang) {
 
         char *highlighted = syntect_to_html(lang.c_str(), "base16-ocean.light", program.c_str());
-        return std::string(highlighted, highlighted + strlen(highlighted));
+
+        if (highlighted) {
+            auto res = std::string(highlighted, highlighted + strlen(highlighted));
+            syntect_release_str(highlighted);
+            return res;
+        } else {
+            spdlog::warn("Failed to highlight code block, bad language? '{}'", lang);
+            return program;
+        }
+
 
         //return oout.str();
     }