Output errors to clog instead of cout

src/main.cpp

@@ -92,7 +92,8 @@ int main(int argc, char* argv[]) {
                     cout << result.first << '\n';
                 }
             } else {
-                cout << "Compilation of " << result.first << " has failed with the following error:\n" << result.second.value().what() << '\n';
+                cout << "Compilation of " << result.first << " has failed with the following error:\n";
+                clog << result.second.value().what() << '\n';
             }
             return is_exception;
         })) {