fix garmin route load failure due to garmin fit format change (#816)

Author: NaturezzZ

run_page/gpxtrackposter/track.py

@@ -101,11 +101,17 @@ def load_fit(self, file_name):
             stream = Stream.from_file(file_name)
             decoder = Decoder(stream)
             messages, errors = decoder.read(convert_datetimes_to_dates=False)
-            # Handle empty fit files that have no distance data
-            if messages.get("total_distance") is None:
-                return
             if errors:
                 print(f"FIT file read fail: {errors}")
+                return
+            if (
+                messages.get("session_mesgs") is None
+                or messages.get("session_mesgs")[0].get("total_distance") is None
+            ):
+                print(
+                    f"Session message or total distance is missing when loading FIT. for file {self.file_names[0]}, we just ignore this file and continue"
+                )
+                return
             self._load_fit_data(messages)
         except Exception as e:
             print(