mavproxy_link.py: correct behaviour with old bindings

some of these MAV_TYPEs are not known in older bindings, e.g. MAV_TYPE_BATTERY.  Avoid fatal errors here when we're working with older bindings

MAVProxy/modules/mavproxy_link.py

@@ -612,6 +612,35 @@ def emit_accumulated_statustext(self, key, id, pending):
             self.status.last_apm_msg_time = time.time()
         del self.status.statustexts_by_sysidcompid[key][id]
 
+    mav_types_which_are_not_vehicles = frozenset([
+        "MAV_TYPE_GCS",
+        "MAV_TYPE_ONBOARD_CONTROLLER",
+        "MAV_TYPE_GIMBAL",
+        "MAV_TYPE_ADSB",
+        "MAV_TYPE_CAMERA",
+        "MAV_TYPE_CHARGING_STATION",
+        "MAV_TYPE_SERVO",
+        "MAV_TYPE_ODID",
+        "MAV_TYPE_BATTERY",
+        "MAV_TYPE_LOG",
+        "MAV_TYPE_OSD",
+        "MAV_TYPE_IMU",
+        "MAV_TYPE_GPS",
+        "MAV_TYPE_WINCH",
+    ])
+
+    mav_autopilots_which_are_not_vehicles = frozenset([
+        mavutil.mavlink.MAV_AUTOPILOT_INVALID,
+        mavutil.mavlink.MAV_AUTOPILOT_RESERVED,
+    ])
+
+    component_ids_which_are_not_vehicles = frozenset([
+        mavutil.mavlink.MAV_COMP_ID_ADSB,
+        mavutil.mavlink.MAV_COMP_ID_ODID_TXRX_1,
+        mavutil.mavlink.MAV_COMP_ID_ODID_TXRX_2,
+        mavutil.mavlink.MAV_COMP_ID_ODID_TXRX_3
+    ])
+
     def heartbeat_is_from_autopilot(self, m):
         '''returns true if m is a HEARTBEAT (or HIGH_LATENCY2) message and
         looks like it is from an actual autopilot rather than from e.g. a
@@ -622,42 +651,23 @@ def heartbeat_is_from_autopilot(self, m):
         if mtype not in ['HEARTBEAT', 'HIGH_LATENCY2']:
             return False
 
-        mav_autopilots_which_are_not_vehicles = frozenset([
-            mavutil.mavlink.MAV_AUTOPILOT_INVALID,
-            mavutil.mavlink.MAV_AUTOPILOT_RESERVED,
-        ])
-        if m.autopilot in mav_autopilots_which_are_not_vehicles:
+        if m.autopilot in LinkModule.mav_autopilots_which_are_not_vehicles:
             return False
 
         # this is a rather bogus assumption - and might break people's
         # setups.  It should probably be removed in favour of trusting
         # the MAV_TYPE field.
-        component_ids_which_are_not_vehicles = frozenset([
-            mavutil.mavlink.MAV_COMP_ID_ADSB,
-            mavutil.mavlink.MAV_COMP_ID_ODID_TXRX_1,
-            mavutil.mavlink.MAV_COMP_ID_ODID_TXRX_2,
-            mavutil.mavlink.MAV_COMP_ID_ODID_TXRX_3
-        ])
-        if m.get_srcComponent() in component_ids_which_are_not_vehicles:
+        if m.get_srcComponent() in LinkModule.component_ids_which_are_not_vehicles:
             return False
 
-        mav_types_which_are_not_vehicles = frozenset([
-            mavutil.mavlink.MAV_TYPE_GCS,
-            mavutil.mavlink.MAV_TYPE_ONBOARD_CONTROLLER,
-            mavutil.mavlink.MAV_TYPE_GIMBAL,
-            mavutil.mavlink.MAV_TYPE_ADSB,
-            mavutil.mavlink.MAV_TYPE_CAMERA,
-            mavutil.mavlink.MAV_TYPE_CHARGING_STATION,
-            mavutil.mavlink.MAV_TYPE_SERVO,
-            mavutil.mavlink.MAV_TYPE_ODID,
-            mavutil.mavlink.MAV_TYPE_BATTERY,
-            mavutil.mavlink.MAV_TYPE_LOG,
-            mavutil.mavlink.MAV_TYPE_OSD,
-            mavutil.mavlink.MAV_TYPE_IMU,
-            mavutil.mavlink.MAV_TYPE_GPS,
-            mavutil.mavlink.MAV_TYPE_WINCH,
-        ])
-        if m.type in mav_types_which_are_not_vehicles:
+        found_mav_type = False
+        # not all of these are present in all versions of mavlink:
+        for t in LinkModule.mav_types_which_are_not_vehicles:
+            if getattr(mavutil.mavlink, t, None) is not None:
+                found_mav_type = True
+                break
+
+        if not found_mav_type:
             return False
 
         return True