Update LiveMeter.py

Author: BFergerson

sourceplusplus/models/instrument/LiveMeter.py

@@ -24,6 +24,9 @@ def from_json(cls, json_str):
         for key in json_dict:
             setattr(meter, key, json_dict[key])
         meter.location = LiveSourceLocation(json_dict["location"]["source"], json_dict["location"]["line"])
-        meter.throttle = HitThrottle(json_dict["throttle"]["limit"], ThrottleStep(json_dict["throttle"]["step"]))
+        
+        if "throttle" in json_dict:
+            meter.throttle = HitThrottle(json_dict["throttle"]["limit"], ThrottleStep(json_dict["throttle"]["step"]))
+
         meter.type = LiveInstrumentType.METER
         return meter