Error while adding/defining new Decay Channel (muonium)

To simulate muonium physics, I first defined the muonium particle/bound system (made up of an antimuon and an electron) using the code used by PSI in their software musrSim. After this I added the most basic decay channel (simply decaying into its constituent fundamental particles, tried using phase space decay as well as the general decay channel) using a physics constructor, and then further adding that into the used physics lists. I have been getting an error as below, and am not sure how to go about it further (I have set the BR equal to 1, but the error keeps persisting)

I am also attaching the codes for the decay channel as well as the physics constructor. Any help as to how to proceed would be much appreciated. Feel free to ask further questions if resources or the question is/are unclear. (2.7 KB) (3.7 KB)