Update position to 0 when user assetPositions is empty (#34)

Author: GavinPHR

examples/basic_adding.py

@@ -166,6 +166,8 @@ def poll(self):
                     self.position = float(position["position"]["szi"])
                     print(f"set position to {self.position}")
                     break
+            if self.position is None:
+                self.position = 0.0
             time.sleep(10)