FIx capitalization in CombinedError bindings

[Schmavery]

Right now this is always null, since we don't match https://github.com/FormidableLabs/urql/blob/f4b11379e43ef14bbc2a5bf563a6aa2cc09b4271/src/utils/error.ts#L43

Probably we should also update graphqlErrors in the record to match, but since that's a breaking change, I thought it might be best done as part of something in #106?

[parkerziegler]

Thanks @Schmavery, good catch! Yep, I'll have some updates for #106 b/t today and tomorrow sometime, so I'm thinking we'll release this plus those changes in a new minor version (since, as you point out, these are all breaking changes). Does that sound good to you?

[Schmavery]

Sounds good. Your call if you wanna do breaking changes in a minor version, doesn't affect my usage too much.