Constructing module should never panic

[dalcde]

This is a special case of #100 that I hope we would agree on.

Here are examples that currently panic:

{"type" : "finite dimensional module", "name": "", "p": 7, "generic": true, "gens": {"x0": 0, "x1": 1}, "actions": ["Sq1 x0 = x1"]}

{"type" : "finite dimensional module", "name": "", "p": 4, "generic": true, "gens": {"x0": 0}}

[hoodmane]

It's not really clear that we disagree about this at all tbh. Panics are bad. The code exposed to the user should not panic. The only convenient way to prevent the json loader from panicking is for the json loader code to return a Result because it has complicated invariants.

For complex invariants, return a Result. If it's just "don't index an array beyond the array bounds" type stuff, we can ask for permission in the wrapper code. If it's of low to moderate complexity, either return a Result or add a "permission" function.

Btw, what is wrong with the first module? Is it that it should say "b x0 = x1"?

[dalcde]

It's not really clear that we disagree about this at all tbh. Panics are bad. The code exposed to the user should not panic. The only convenient way to prevent the json loader from panicking is for the json loader code to return a Result because it has complicated invariants.

Sure. But I think it is a good idea to make it a separate issue because this is specific enough.

Btw, what is wrong with the first module? Is it that it should say "b x0 = x1"?

Currently it fails because it tries to look up P^1, which is in degree 2 * 7 - 2, but we have only computed the algebra up to degree 1 because that's what the maximum degree is. The fact that we have inconsistent degrees does not currently cause a panic. The second one is now fixed.