Fix compatibility path generation in read_json_files().

src/files.cpp

@@ -13,7 +13,6 @@
  *  You should have received a copy of the GNU Affero General Public License
  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-
 #include "files.hpp"
 
 #include "fs-compat.hpp"
@@ -194,7 +193,7 @@ vector<entry_type> read_json_files(const bool cache)
                 const fs::path sh_path{screenshot};
                 // clang-format off
                 const auto compat_path{path.parent_path() /= path.stem()
-                                       /= sh_path.extension()};
+                                       += sh_path.extension().string()};
                 // clang-format on
                 if (entry.screenshot_filepaths.size() == 1
                     && fs::exists(compat_path))