chore: check InsufficientData before index access

[tisonkun]

We may later build a shared serde utils where deserialize use a cursor like #23 so we can check insufficient data on the fly, and advancing the curosr on reading to avoid hardcode offset.

[tisonkun]

cc @notfilippo @freakyzoidberg what do you think? So far, it's OK to let the first 2 or 3 impls uses their own logics but we may later have a generally similar serde workflow.

[notfilippo]

we may later have a generally similar serde workflow.

I think it's fine to wait a couple of sketches to be merged before we start unifying the interface. Might help identifying parallels between different implementations.

[notfilippo]

What's the idea behind this? Do we have tools to enforce this style repo-wide?

[tisonkun]

I found it when a mod name sometimes conflicts with a dependency name. Using self::sketch::HllSketch always unambiguously refers to the proper symbol.

Do we have tools to enforce this style repo-wide?

Not quite easy. One can define a custom clippy rule or work with ast-grep. But this rule depends on whether the (pub use) symbol is within this crate/module.