demonstrate the problems by removing my workarounds

[Jumpy-Squirrel]

This branch contains an extra commit that removes two of my most ugly workarounds.

On the first one (addon.tsx), if you inspect value.addons in the debugger, it very much has a field "selected". But somehow the typescript compiler doesn't seem to understand this.

The second one is even more confusing (register.ts). The error message of npm run tsc is:

src/state/selectors/register.ts:60:40 - error TS2339: Property 'count' does not exist on type '{ readonly count: "c1" | "c2" | "c3" | "c4" | "c5" | "c6" | "c8" | "c10" | "c15" | "c20" | "c30" | "c40" | "c50" | "c100"; } | { readonly count: "c1" | "c2" | "c3" | "c4" | "c5" | "c6" | "c8" | "c10" | "c7" | "c9"; } | ... 28 more ... | {}'.
  Property 'count' does not exist on type '{ readonly size: "XS" | "S" | "M" | "L" | "XL" | "XXL" | "m3XL" | "m4XL" | "wXS" | "wS" | "wM" | "wL" | "wXL" | "wXXL" | "w3XL" | "w4XL"; }'.

huh? Property 'count' does not exist on type '{ readonly count: ...

Yeah, I know it does not exist on ALL possible types, but that's what the ?.count is for, right?