possible bug when using update_params() on flexmodel_to_calibrate objects

[papsti]

see 6484d79 for a reprex

not sure if this is intended behaviour or if it's a bug... i'm just trying to manually update some parameters in a flexmodel_to_calibrate object so that simulation_history() uses those updated parameters. i'm using update_params() but the updated values aren't reflected in the sims...

i can circumvent this in the code i'm developing by toting around the original flexmodel object and just updating paramteres in that for simulation. i've tried using as.flexmodel() on the flexmodel_to_calibrate object to try to coerce it into behaving predictably with simulation_history(), but hilariously attempts at simulation_history(as.flexmodel(mod)) where mod is a flexmodel_to_calibate object crash my RStudio session 🙃