`spend` fails without descriptive error about plutus-simple-model

[AgustinBadi]

Hi @Renegatto !

There's a function called withSpend :: PubKeyHash -> Value -> (UserSpend -> Run ()) -> Run () that serves the same purpose as spend and logs an error if an user doesn't have enough funds. Maybe that can be an awnser to your requirement, or could be that there are other errors that should be catched from your point of view?

Greetings,

[Renegatto]

Hi, @AgustinBadi.
It's good that such a function exists, but in general in a program (especially in a library) when a function fails it should be clear where and/or why.
I think Exception: Maybe.fromJust: Nothing is not something we expect to see when using library which is not base.

The solution is simply throwing custom (not necessary defined by the library user) error on Nothing instead of using fromJust.