build error

[nissy-dev]

Hi !!
I got the following error when I tried to contribute to this repo and I did npm run build.

src/widlprocess.ts:178:59 - error TS2531: Object is possibly 'null'.

178         if (extAttr.name === "NamedConstructor" && typeof extAttr.rhs.value === "string") {
                                                              ~~~~~~~~~~~


src/widlprocess.ts:180:23 - error TS2531: Object is possibly 'null'.

180                 name: extAttr.rhs.value,
                          ~~~~~~~~~~~


error Command failed with exit code 2.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.