When trying to get the value of a value type Property that is not set with TryGetValue<> I get a NullReferenceException. This since the property value returns null when empty and TryGetValue tries to cast the value to the given type. PropertyNumber, PropertyFloatNumber, PropertyBoolean, PropertyCategory, PropertyDateTime all behaves like this.
Can you confirm that this is not the expected behavior of value type properties?
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This is most definitely a bug. It has been entered as 7386: PropertyDataCollection.TryGetValue<> cannot handle an empty value type properties.
Thank you for the report!