Get null pointer exception if property change via mqtt

Since I change to ThingWorx 8 I have a big trouble with setting property values via mqtt.

I send messages like this via mqtt to an thing (base type mqtt)

{ "temp":3.1,

"brightness":11.2,

"name":"climateSensor_3",

"humidity":5.3,

"pressure":6.4,

"CO2concentration":8.5 }

This message will set in a property of the thing named MQTTValue (type json). If MQTTValue change I call a subscriber which will set all properties of the think to the properties of the message:

var newVal = eventData.newValue.value;

me.temp = newVal.temp;

me.humidity = newVal.humidity;

...

I surrounded it by a try catch.

Everytime I get a mqtt message where a value is changed I get an null pointer exception at the set-line.

Example:

All properties of the climateSensor_3 thing are set to 10. Now a new mqtt message arrived where every property is also 10:

{ "temp":10.0,

"brightness":10.0,

"name":"climateSensor_3",

"humidity":10.0,

"pressure":10.0,

"CO2concentration":10.0 }

==> no exception

Now a other mqtt message arrived where one property is not the same like the old value:

{ "temp":20.0,

"brightness":10.0,

"name":"climateSensor_3",

"humidity":10.0,

"pressure":10.0,

"CO2concentration":10.0 }

==> null pointer exception in line "me.temp = newVal.temp;"

If the message would be like this:

{ "temp":10.0,

"brightness":20.0,

"name":"climateSensor_3",

"humidity":10.0,

"pressure":10.0,

"CO2concentration":10.0 }

I get the error on line "me.brightness = newVal.brightness;"

Another strange thing is I get the null pointer exception but the value is still changed.