Catch exception to skip invalid file

[hugovk]

Fixes #23.

I have a GPX file with a first <trkpt> element like this:

      <trkpt>
        <ele>31.2</ele>
        <time>2019-08-31T09:02:36Z</time>
        <extensions>
          <gpxdata:temp>0</gpxdata:temp>
        </extensions>
      </trkpt>

It's missing lon and lat elements. The rest look like this:

      <trkpt lon="24.12345" lat="60.12345">
        <ele>31.2</ele>
        <time>2019-08-31T09:02:37Z</time>
        <extensions>
          <gpxdata:temp>29</gpxdata:temp>
        </extensions>
      </trkpt>

Running on a directory containing it causes an exception: gpxpy.gpx.GPXException: latitude is mandatory in None (got None). Also, we don't know which file causes the problem.

Full traceback

```pytb Processing data... Processing ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 0% -:--:-- multiprocessing.pool.RemoteTraceback: """ Traceback (most recent call last): File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/multiprocessing/pool.py", line 125, in worker result = (True, func(*args, **kwds)) ^^^^^^^^^^^^^^^^^^^ File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/stravavis/process_data.py", line 13, in process_file return process_gpx(fpath) ^^^^^^^^^^^^^^^^^^ File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/stravavis/process_data.py", line 21, in process_gpx activity = gpxpy.parse(open(gpxfile)) ^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/gpxpy/__init__.py", line 39, in parse return parser.parse(version) ^^^^^^^^^^^^^^^^^^^^^ File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/gpxpy/parser.py", line 154, in parse mod_gpxfield.gpx_fields_from_xml(self.gpx, root, version) File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/gpxpy/gpxfield.py", line 590, in gpx_fields_from_xml value = gpx_field.from_xml(current_node, version) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/gpxpy/gpxfield.py", line 241, in from_xml result.append(gpx_fields_from_xml(self.classs, child, ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/gpxpy/gpxfield.py", line 590, in gpx_fields_from_xml value = gpx_field.from_xml(current_node, version) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/gpxpy/gpxfield.py", line 241, in from_xml result.append(gpx_fields_from_xml(self.classs, child, ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/gpxpy/gpxfield.py", line 590, in gpx_fields_from_xml value = gpx_field.from_xml(current_node, version) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/gpxpy/gpxfield.py", line 241, in from_xml result.append(gpx_fields_from_xml(self.classs, child, ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/gpxpy/gpxfield.py", line 590, in gpx_fields_from_xml value = gpx_field.from_xml(current_node, version) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/gpxpy/gpxfield.py", line 197, in from_xml raise mod_gpx.GPXException(f'{self.name} is mandatory in {self.tag} (got {result})') gpxpy.gpx.GPXException: latitude is mandatory in None (got None) """ The above exception was the direct cause of the following exception: Traceback (most recent call last): File "/Library/Frameworks/Python.framework/Versions/3.11/bin/stravavis", line 8, in sys.exit(main()) ^^^^^^ File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/stravavis/cli.py", line 51, in main df = process_data(args.path) ^^^^^^^^^^^^^^^^^^^^^^^ File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/stravavis/process_data.py", line 108, in process_data processed = list(it) ^^^^^^^^ File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/rich/progress.py", line 168, in track yield from progress.track( File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/rich/progress.py", line 1215, in track for value in sequence: File "/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/multiprocessing/pool.py", line 873, in next raise value gpxpy.gpx.GPXException: latitude is mandatory in None (got None) ```

Let's catch this exception and instead skip the problematic file. Let's also print the filename so the user can check what the problem is (in my case I can manually delete the bad <trkpt> and try again).

$ stravavis tests/gpx
Processing data...
Processing ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━   0% -:--:--
Skipping tests/gpx/invalid-lon-lat-missing.gpx: GPXException: latitude is mandatory in None (got None)
Processing ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 100% 0:00:00
Plotting facets...
Saved to strava-facets.png
Plotting map...
Plotting activities ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 100% 0:00:00
Saved to strava-map.png
...