Status Chart: chart.js 3.6.0, improve type info, weekly updates

[StephanTLavavej]

• npm update.
• README.md: Update Node.js version.
• chart.js 3.6.0.
  • This fixes Bar: fix too thick borders chartjs/Chart.js#9678, noted in Status Chart: Weekly updates, chart.js 3.5.0 #2100.
• weekly_table.js updates.
• gather_stats.ts: Improve type info.
  • Various raw fields can be null. (For author, this is when a user has been deleted; for closedAt/mergedAt, this is when a PR/issue hasn't been closed/merged.) We're already testing for null, this just acknowledges that in the type system.
  • Add types for the RateLimit and combined RawNodes that retrieve_nodes_from_network() and retrieve_nodes() return.
  • As we gradually build up the information for RateLimit, TypeScript is intelligent enough to see that spent/remaining/limit will always be number instead of null by the time we return, making the RateLimit type more useful. To achieve this, we need individual variables in retrieve_nodes_from_network(). We can say that spent/remaining/limit are number without an initializer, and TypeScript will require that we assign to them before using them. We need to change the while loop into a do/while loop so that TypeScript will see that it always runs at least one iteration (this was already guaranteed because variables.want_prs and variables.want_issues are initially true).
  • In retrieve_nodes(), we need a type assertion (as RawNodes) to tell the compiler what we're loading.
  • In warn_about_duplicates(), constructing Set<string> tells TypeScript what we're doing (otherwise we're working with Set<any>).
  • Similarly, in write_monthly_table(), we're really using a Map<string, number>.
  • After thinking about it, I've changed transform_pr_nodes() and transform_issue_nodes() to have deduced return types (with explicitly typed ret variables). This is more consistent with the rest of the code now, and while both ways are equally type-checked, the ret variables offer better diagnostics if the types are wrong (as TypeScript doesn't have to complain about the huge transformation in the function).

📈 Live preview: stephantlavavej.github.io/STL/