Feature request: make "context in exceptions" optional

[vanschelven]

I'm using fjs to generate python code that does the validation (i.e. compile_to_code)

I'm working around #72 by just falling back to good (bad) old jsonschema and best_guess in the case I have a validationerror.

That means I don't use any of the information that's present in the JsonSchemaValueException. Looking at that code, I noticed that ~75% (out of a whopping 2.5MB) is used by the definition parts of the generated exceptions. When you have deeply nested definitions, that is to be expected, since the relevant part of the definition (for some part) is repeated throughout the tree.

Since I don't use that information, generating it (and loading it) seems wasteful. It would be nice if compile_to_code had a parameter that controlled the behavior of the generated raise JsonSchemaValueException, basically making (the relevant parts of) this commit conditional.

I managed to work around this a bit by hacking around in def exc but that doesn't "quite feel right".