dcodeIO

Removing the `good first issue` label here, because this might become quite tricky. Not super tricky, but potentially too tricky for a very first issue.

Isn't the issue rather the value in, say, `types.defaults["int64"]`? Already does a lookup there, whereas the new `isLongType` seems redundant on this basis.

The issue is patched since 6.11.4 respectively 7.2.5, as per [CVE-2023-36665](https://github.com/advisories/GHSA-h755-8qp9-cq85).