TypedStore should .unwrap() the return value from C::decode

[rnbguy]

The following Options (indicates failure to decode) are subsumed by parent Option from .set/.get ` (indicates unset path in the store)

basecoin-rs/crates/store/src/types/store.rs

Line 56 in dc3b43a

.map(|prev_val| prev_val.and_then(|v| C::decode(&v)))

basecoin-rs/crates/store/src/types/store.rs

Line 68 in dc3b43a

.and_then(|v| C::decode(&v))

The C::encode calls are correctly .unwrap-ed in the same file.

basecoin-rs/crates/store/src/types/store.rs

Line 54 in dc3b43a

C::encode(&value).unwrap().as_ref().to_vec(),

basecoin-rs/crates/store/src/types/store.rs

Line 90 in dc3b43a

.set(path.to_string().into(), NullCodec::encode(&()).unwrap())

The best solution is to return Result from C::encode and C::decode as outlined in #152 and appropriately handle them in TypedStore - probably return Option<Result<_, _>>.