Compilation failure when building for non-assigner target

[aleasims]

When building code with zkLLVM types for non-assigner target (e.g. x86‑64) you will most likely get a segmentation fault.

Example:

fn main() {
    let x: __zkllvm_field_pallas_base = 1g;
    if x + 1g == 2g {
        println!("x is one");
    }
}

— this code causes a segmentation fault at compilation.

Of course we can't compile such code for any non-assigner target. However it would be nice to have something more user-friendly than a segmentation fault.