Fix : Apidae Trek parser now ignores when no linestring in GPX

Previously caused a crash.

geotrek/trekking/parsers.py

@@ -922,6 +922,8 @@ def _get_geom_from_gpx(data):
                 geos = ApidaeTrekParser._maybe_get_linestring_from_layer(layer)
                 if geos:
                     break
+            else:
+                raise RowImportError("No LineString feature found in GPX layers tracks or routes")
             geos.transform(settings.SRID)
             return geos