mavpicviewer: handle arithmetic exception in image viewer

MAVProxy/tools/mavpicviewer/mavpicviewer_image.py

@@ -430,11 +430,15 @@ def update_map(self):
         if self.sm is not None:
             self.sm.set_center(self.lat, self.lon)
 
-        projection1 = self.cam1_projection.get_projection(self.lat, self.lon, self.alt_amsl, self.roll, self.pitch, self.yaw)
-        if projection1 is not None and self.sm is not None:
-            self.sm.add_object(mp_slipmap.SlipPolygon('projection1', projection1, layer=1, linewidth=2, colour=mpv.RGB_GREEN))
-        else:
-            print(prefix_str + "failed to add projection to map")
+        # calculate image outline polygon for map
+        try:
+            projection1 = self.cam1_projection.get_projection(self.lat, self.lon, self.alt_amsl, self.roll, self.pitch, self.yaw)
+            if projection1 is not None and self.sm is not None:
+                self.sm.add_object(mp_slipmap.SlipPolygon('projection1', projection1, layer=1, linewidth=2, colour=mpv.RGB_GREEN))
+            else:
+                print(prefix_str + "failed to add projection to map")
+        except ArithmeticError as e:
+            print(prefix_str + "failed to add projection to map due to arithmetic error: " + str(e))
 
     # add a rectangle specified by two locations to the map
     def add_rectangle_to_map(self, name, lat1, lon1, lat2, lon2):