The issue is already reported in the GitLab under spis/dev/num-plugins#4 (https://code.spis.org/spis/dev/num-plugins/-/issues/4) but copied here for broader audience:
Hello,
We are simulating an EP thruster with SPIS 6.1.0 and experience the following error: When we turn off the cathode and thruster in the Cathode_1 and Thruster_1 instruments (cathodeON = 0 and thrusterON = 0 in “interaction parameters”) at the beginning of the simulation and define a scheduled start time, the SPIS simulation crashes and provides the following error message in the console: Spis.Util.Exception.SpisRuntimeException: Cannot scale m-3 to s-1 at spis.Util.Phys.Unit.getDoubleScalingFactorTo(Unit.java:447) Keeping the thruster and cathode turned on (cathodeON = 1 and thrusterON = 1 in “interaction parameters”) and scheduling a stop time works properly (see the attached plot of the electric propulsion device currents).
